Knowledge

Frequently Asked Acne Questions

What is Acne?

Type 3 Acne on Forehead
Type 3 Acne on Forehead

Acne is a difficult to treat and often debilitating disease that affects the skin, usually the face. The most common form of acne (acne vulgaris) is an infection within a hair follicle. This infection causes varying degrees of inflammation, which manifest as pimples, nodules and cysts. When the inflammation is severe, it can cause permanent damage to the skin and create acne scars. This section covers the basics of what acne is and the different types of acne.

Frequently Asked Acne Questions

Frequently Asked Acne QuestionsThere are many claims about what causes acne and what treatments are effective for improving acne symptoms. Some of these claims are entirely true, some are partially true, and many are completely false. There is also a tremendous amount of contradictory information about acne available from lots of different sources. In the FAQs section we address the most common acne-related questions on topics such as diet, hygiene, bacteria, hormones and more.

Acne Science

Acne ScienceAcne is a complex disease. There are many factors that contribute to the development of acne symptoms, and they vary greatly between individuals. The Acne Science section covers a range of scientific topics related to the development of acne and the available treatments.

Acne Treatments

Over The Counter (OTC) Acne Products
Over The Counter (OTC) Acne Products

Choosing the best acne treatment(s) for each individual depends on many factors. The type and severity of your acne, your age, gender, treatment history and personal preferences are all important. If possible, you should work with your dermatologist or healthcare provider to develop a comprehensive acne treatment plan that is specifically tailored to your needs. Treatments for active acne and acne scars can be roughly divided into 6 different categories: Over The Counter (OTC) Treatments, Pharmaceutical (Rx) Treatments, Naturopathic/Homeopathic Treatments, Light & Laser Treatments, Surgical Treatments and Acne Scar Treatments. This section contains detailed information about all of the available acne treatments.

Acne Science

Acne Science

Acne is a complex disease. The Acne Science section covers a range of scientific topics related to the development of acne and the available treatments. For more discussions about common acne questions, refer to our Frequently Asked Acne Questions page.

What Causes Acne?

Inflammatory Acne Papules Skin and Cellular View
Inflammatory Acne Papules Skin and Cellular View

Acne is a complex disease and many factors can contribute to the development of acne symptoms. Every case of acne is unique and the blend of factors that cause acne varies between individuals. This section contains a list and discussion about the factors that are major contributors to the development of acne symptoms.

Acne at a Cellular Level

Whitehead Pimple Skin and Cellular View
Whitehead Pimple Skin and Cellular View

Most people can recognize acne when it presents on the face or body. Most people also have the vague understanding that acne is associated with oily skin and an excess production of sebum. But beyond that, few people really grasp what is actually happening at the microscopic level of a pimple. This section discusses the formation of acne lesions at a microscopic level.

The Sebaceous Glands

Hair Follicle, Sebaceous Glands and Sebum (Wikipedia)
Hair Follicle and Sebaceous Glands (Wikipedia)

Sebaceous glands produce and secrete sebum, which is responsible for moisturizing and protecting skin and hair. Sebaceous glands are essential components of healthy skin. Damaged or malfunctioning sebaceous glands contribute to many dermatological conditions, including acne vulgaris. This section discusses the structure and function of the sebaceous glands.

Sebum

Composition of Human Sebum
Composition of Human Sebum

Sebum is a naturally occurring substance that moisturizes, lubricates and protects the skin and hair. Sebum is produced by the sebaceous glands of mammals. Healthy sebum production is essential for the integrity and normal function of the skin as a protective organ. Sebum is also an important source of energy (food) for acne-causing Propionibacterium acnes bacteria. This section discusses the biology of sebum and its role in the development of acne symptoms.

What is Propionibacterium acnes?

Propionibacterium acnes (Toyoda, et al)
Propionibacterium acnes (Toyoda, et al)

Propionibacterium acnes (P.acnes) is a bacteria that can colonize the the skin and hair follicles. Excessive growth of this bacteria in the skin contributes to acne vulgaris. Propionibacterium acnes (P. acnes) is a bacteria that grows deep inside of pores, where it feeds on the sebum that is produced by the sebaceous glands that surround the base of the hair shaft. Most individuals with acne symptoms have an overgrowth of P. acnes bacteria in their skin. Several research studies have indicated that specific strains of P. acnes bacteria are commonly associated with acne vulgaris. This section details what P. acnes bacteria are and how it contributes to acne symptoms.

The Antibiotic Susceptibility of Propionibacterium acnes

Bacteria Antibiotic Susceptibility Test Plate (credit - Wikipedia)
Bacteria Antibiotic Susceptibility Test Plate (Wikipedia)

Propionibacterium acnes is a bacteria that grows within hair follicles and contributes to acne symptoms. Antibiotics reduce the growth of acne-causing bacteria and are a common treatment for acne symptoms. For the past 50 years, physicians and researchers have been screening the susceptibility of Propionibacterium acnes (P. acnes) bacteria to different antibiotics. The results from these studies clearly demonstrate that in many places, P. acnes bacteria are becoming increasingly resistant to certain classes of antibiotics. This section discusses the results of research studies about the antibiotic sensitivity of P. acnes bacteria.

The Antibiotic Families

Tetracycline Antibiotic Capsules
Tetracycline Antibiotic Capsules

There are many different families of antibiotics. Each antibiotic family targets bacteria in a unique way. Each antibiotic family tends to be more effective against certain types of bacteria, and less effective against others. Antibiotics from several different families are used for the treatment of acne. Antibiotics can be used applied topically or ingested orally. The route of delivery, the ability of an antibiotic to accumulate in the skin and the susceptibility of P. acnes bacteria to an antibiotic all impact the efficacy of a given antibiotic treatment. This section discusses the different classes of antibiotics that are used in the treatment of acne.

How Do Bacteria Become Resistant to Antibiotics?

Bacteria Cell (Wikipedia)
Bacteria Cell (Wikipedia)

Bacteria can become resistant to antibiotics that they were susceptible to in the past. There are several factors which contribute to the growing problem of antibiotic-resistant bacteria. This section discusses the many ways that antibiotic resistance may occur, as well as the conditions and environments that promote the development of antibiotic-resistant bacteria.

The Antibacterial Activity of Essential Oil

Eucalyptus Essential Oil Vials
Eucalyptus Essential Oil Vials

Many essential oils and other plant extracts have antimicrobial properties which can be helpful for health and wellness applications. There is an incredible diversity of essential oils and other plant extracts available on the market today. This selection provides a plethora of options for both professional and casual practitioners of Naturopathic remedies for many health issues, including acne. This section discusses the scientific research into the antibacterial properties of plant essential oils.

Avoiding Negative Interactions Between Medications

Physicians Desk Reference (PDR)
Physicians Desk Reference (PDR)

A medication is contraindicated when there is an existing condition that makes its use inadvisable. Certain medications can be contraindicated in specific groups of people (eg. pregnant women) or in combination with other medications (eg. aspirin and warfarin). Basically, some medications are contraindicated with one another because taking them together is known to cause potentially serious problems. This section discusses how to learn more about medications and avoid negative drug interactions.

How Do Acne Scars Form?

Ice Pick Acne Scars on Cheek
Icepick Acne Scars on Cheek

Acne scars are the result of tissue damage caused by inflammatory acne. The vast majority of acne scars are caused by from persistent cases of inflammatory acne affecting the same area of skin. Individuals who suffer from frequent nodular and cystic acne outbreaks (Acne Types: 3-4) are at a very high risk of developing permanent acne scarring. This is particularly true when a region is affected by overlapping acne outbreaks, with no opportunity for the skin to completely heal between outbreaks. This section discusses the different factors that contribute to the development of acne scars.

Frequently Asked Acne Questions

Frequently Asked Acne Questions

There are many claims about what causes acne and what treatments are effective for improving acne symptoms. Some of these claims are entirely true, some are partially true, and many are completely false. There is also a tremendous amount of contradictory information about acne available from lots of different sources.

In this FAQs section we address the most common acne-related questions on topics such as diet, hygiene, bacteria, hormones and more. For in-depth discussions the scientific aspects of acne, refer to our Acne Science page.

What is Acne?

Type 3 Acne on Forehead
Type 3 Acne on Forehead

Acne is a difficult to treat and often debilitating disease that affects the skin, usually the face. The most common form of acne (acne vulgaris) is an infection within a hair follicle. This infection causes varying degrees of inflammation, which manifest as pimples, nodules and cysts. When the inflammation is severe, it can cause permanent damage to the skin and create acne scars. This section covers the basics of what acne is and the different types of acne.

What Causes Acne?

Inflammatory Acne Papules Skin and Cellular View
Inflammatory Acne Papules Skin and Cellular View

Acne is a complex disease and many factors can contribute to the development of acne symptoms. Every case of acne is unique and the blend of factors that cause acne varies between individuals. This section contains a list and discussion about the factors that are major contributors to the development of acne symptoms.

What is the Best Acne Treatment for Me?

Over The Counter (OTC) Acne Products
Over The Counter (OTC) Acne Products

Choosing the best acne treatment(s) for each individual depends on many factors. The type and severity of your acne, your age, gender, treatment history and personal preferences are all important. If possible, you should work with your dermatologist or healthcare provider to develop a comprehensive acne treatment plan that is specifically tailored to your needs. Treatments for active acne and acne scars can be roughly divided into 6 different categories: Over The Counter (OTC) Treatments, Pharmaceutical (Rx) Treatments, Naturopathic/Homeopathic Treatments, Light & Laser Treatments, Surgical Treatments and Acne Scar Treatments. This section contains detailed information about all of the available acne treatments.

What are the Different Types of Acne Scars?

Rolling Acne Scars on Face (Woo)
Rolling Acne Scars on Face (Woo)

Acne scars come in many different shapes, sizes and even colors. Each type of acne scar has its own unique characteristics and features. Because of these differences, the available treatments for acne scars are not one size fits all. It is important to carefully choose the treatment that best matches your needs in order to achieve optimal results. Acne scars can be classified into three main groups: Depressed (pitted scars), Raised (keloid scars) and Discoloration scars. This section discusses the different types of acne scars and the features that define each group.

How Do Acne Scars Form?

Ice Pick Acne Scars on Cheek
Icepick Acne Scars on Cheek

Acne scars are the result of tissue damage caused by inflammatory acne. The vast majority of acne scars are caused by from persistent cases of inflammatory acne affecting the same area of skin. Individuals who suffer from frequent nodular and cystic acne outbreaks (Acne Types: 3-4) are at a very high risk of developing permanent acne scarring. This is particularly true when a region is affected by overlapping acne outbreaks, with no opportunity for the skin to completely heal between outbreaks. This section discusses the different factors that contribute to the development of acne scars.

Is acne caused by dirt or not washing my face enough?

Facial Cleansers are Popular OTC Acne Products
Facial Cleansers are Popular OTC Acne Products

The answer is usually NO. In most acne lesions (pimples, nodules, cysts, etc.), the site where the infection and inflammation is centered is not near the surface of the skin. Instead, it is near the base of the hair follicle where the sebaceous gland attaches. This is a region of the follicle that is not readily accessible from the surface. Therefore, cleansers and their active ingredients are unlikely to impact the inflammatory processes that drive moderate to severe acne symptoms (Acne Types: 2-4). This section discusses the benefits, risks and uses of acne facial cleansers.

Is Popping a Pimple a Bad Idea?

Popping a Pimple
Popping a Pimple

The answer is that it can be, especially if done improperly. Some pimples and other acne lesions benefit from being drained or popped in order to remove pus and accelerate healing, but other pimples should be left alone to heal on their own. The nodules and cysts of those patients who suffer from severe inflammatory acne (Acne Type: 4) are often lanced and drained by a dermatologist. This can prevent further damage and limit post-acne scarring. The important thing is to identify those zits and pimples which can be effectively popped (and which ones can not), and to do that properly and in a sterile fashion. This section discusses the risks, benefits and techniques for draining acne lesions.

Does Greasy Food, Milk or Chocolate Cause Acne?

Does Pizza Cause Acne?
Does Pizza Cause Acne?

The answer is probably not. Anecdotal associations between acne and particular foods like chocolate, ice cream and pizza have largely been discredited by scientific research. But research does point to a connection between overall diet and the development of acne symptoms. Researchers have shown that people whose diets include lots of high glycemic index foods (foods that are high in sugar and simple carbohydrates) tend to experience acne at a greater frequency than those who have low glycemic index diets. However, there is no clear scientific consensus on why this connection exists. This section discusses several of common claims about the association of specific types of food and acne symptoms.

What Does Non-Comedogenic Mean?

Acne Patients Should Avoid Comedogenic Substances
Acne Patients Should Avoid Comedogenic Substances

Comedogenicity refers to the potential of a substance to cause a comedo, a plugged or inflamed pore. Non-comedogenic means that in testing, the substance or product has not been shown to cause comedos (clogged or inflamed hair follicle). Some substances (eg. coal tar) are highly comedogenic and produce a type of allergic, acne-like reaction. There is not a clear consensus when it comes to the comedogenicity of many substances, with different tests yielding different results. This section discusses what comedogenicity is, how it is tested and which products and substances are likely to be comedogenic.

Can Stress Cause Acne?

Stressed Out
Stress

Stress can inhibit the function of the immune system and trigger or worsen acne symptoms It is well known that putting an organism under stress makes it more susceptible to infection. This is true for humans, animals and even plants. The same neural and biochemical pathways that make stress feel uncomfortable can also disrupt the delicate balance of a properly functioning immune system. This section discusses the relationship between stress and the development of acne symptoms.

What is the Relationship Between Acne, Depression and Suicide

Diagram of Psychological Impact of Acne (Magin)
Diagram of Psychological Impact of Acne (Magin)

Acne can have a profound negative impact on the psychological well-being of acne sufferers. Acne can increase the risk of bullying, depression and suicide.
For the millions of people who have suffered with acne, the psychological toll of the disease is well understood. The face is the window that connects one’s consciousness with the outside world. The face is also an essential factor in how the outside world perceives an individual. More than any other part of the body, diseases that affect the appearance of the face can have severe emotional and psychological consequences. This section discusses the connections between acne, stress, depression and suicide.

Is Acne Different Between Men and Women?

Acne Tends to be Different Between Men and Women
Acne Tends to be Different Between Men and Women

Yes, and it mostly comes down to hormones. Men and women tend to experience acne differently. Men are more likely to develop acne during puberty and are more likely to develop severe and inflammatory forms of the disease. Acne symptoms tend to peak during adolescence and recede during a male’s mid 20’s. In contrast, women tend to experience less acne and less severe acne than men, but rates of acne actually increase for women in the 20-40 age range. This section discusses key differences in acne symptoms between men and women, and why these differences exist.

What is the Relationship Between Pregnancy and Acne?

Pregnancy can Trigger Acne Symptoms in Some Women
Pregnancy can Trigger Acne Symptoms in Some Women

There are a tremendous number of changes that take place in the female body during pregnancy and these changes can have both positive and negative effects on acne symptoms.
Many women experience dramatic changes in their acne both during and after pregnancy. Hormones that control the natural processes of menstruation and pregnancy have wide ranging effects throughout the body. Onset of acne or a worsening of acne symptoms is very common during pregnancy. At the same time, a smaller percentage of women report an improvement in their acne symptoms during pregnancy. This section discusses the effects that pregnancy can have on acne symptoms.

Anabolic Steroids and Acne

Arnold Used Lots of Anabolic Steroids
Arnold Used Lots of Anabolic Steroids

Anabolic Steroids (aka Roids, Juice, AAS, etc) are molecules that mimic the shape and function of androgen hormones (eg. Testosterone). Anabolic Steroids are generally used to stimulate protein synthesis and muscle growth. They are widely used as performance enhancing drugs (PEDs) in athletics. Anabolic steroids should not be confused with corticosteroids, which are immune suppressants and can actually inhibit muscle growth. Corticosteroid injections are sometimes used to treat acute inflammation in severe acne lesions. Anabolic Steroids are never used as an acne treatment, and their use can cause or worsen acne symptoms. This section discusses the biology of anabolic steroids and their role in the development of acne symptoms.

What is Propionibacterium acnes?

Propionibacterium acnes (Toyoda, et al)
Propionibacterium acnes (Toyoda, et al)

Propionibacterium acnes (P.acnes) is a bacteria that can colonize the the skin and hair follicles. Excessive growth of this bacteria in the skin contributes to acne vulgaris. Propionibacterium acnes (P. acnes) is a bacteria that grows deep inside of pores, where it feeds on the sebum that is produced by the sebaceous glands that surround the base of the hair shaft. Most individuals with acne symptoms have an overgrowth of P. acnes bacteria in their skin. Several research studies have indicated that specific strains of P. acnes bacteria are commonly associated with acne vulgaris. This section details what P. acnes bacteria are and how it contributes to acne symptoms.

Avoiding Negative Interactions Between Medications

Accutan Contraindication from PDR

What Does “Contraindicated” Mean?

Isotretinoin (Accutane) Pregnancy Contraindication Warning
Isotretinoin (Accutane) Pregnancy Contraindication Warning

A medication is contraindicated when there is an existing condition that makes its use inadvisable. Certain medications can be contraindicated in specific groups of people (eg. pregnant women) or in combination with other medications (eg. aspirin and warfarin). Basically, some medications are contraindicated with one another because taking them together is known to cause potentially serious problems. Before using any medication, it is important to verify (preferably through consultation with a licensed medical provider) that the medication is not contraindicated with any medical conditions you may have, or with any medications you may already be taking.

How Can I Check For Contraindications?

Educate Yourself About Your Medications

The more you learn about a particular topic, the more likely you are to make good decisions and avoid mistakes when dealing with that topic. This is especially true for medical conditions and medications. At the end of the day, it is your body and you are responsible for what you put in it (or on it). It is the patient’s responsibility to educate themselves as best as possible about any medications they are taking, or are considering taking.

An excellent way to start educating yourself about the medications that you are taking is by reading the patient inserts that come with a medication. This information outlines many of the important features, and risks, of a medication. For more detailed information, the physician’s insert for the medication is a good start. These can be found online by using google to search for the term “Physician Insert” plus the name of your medication. The Physicians’ Desk Reference is another excellent resource to learn more about medications and their contraindications.

The Physician’s Desk Reference (PDR)

Physicians Desk Reference (PDR)
Physicians Desk Reference (PDR)

The Physicians’ Desk Reference (PDR) is a an annually updated compilation of manufacturers’ prescribing information for prescription medications. It is designed to provide physicians with the all of the legally mandated information relevant to available prescription medications. While it is widely used by medical professionals, it is also a valuable resource for patients and consumers. The Physician’s Desk Reference is available in many libraries, bookstores and online from sources like Amazon.com.

Acne at a Cellular Level

Inflammatory Acne Papules Skin and Cellular View
Whitehead Pimple Skin and Cellular View
Whitehead Pimple Skin and Cellular View

Most people can recognize acne when it presents on the face or body. Most people also have the vague understanding that acne is associated with oily skin and an excess production of sebum. But beyond that, few people really grasp what is actually happening at the microscopic level of a pimple.

Understanding the physiological and pathological processes behind acne can help you sort out what treatments and advice can help you make positive changes in your acne. A better understanding of the science of acne can also help you identify the claims that have no basis in scientific reality and should be ignored.

What Causes Acne?

Healthy and Infected Follicle
Healthy and Infected Follicle

At a very basic level, acne results from a combination of factors that result in blocked pores, an accumulation of sebum, bacterial growth and inflammation. Acne generally occurs within the hair follicle, when excess sebum is produced by the sebaceous glands and creates a plug that blocks the follicle.

Clogged follicles create a micro-environment that favors the growth of certain types of bacteria, such as Propionibacterium acnes and Staphylococcus aureus. The presence of this bacteria triggers an immune response, which is characterized by inflammation, increased blood flow (redness) and the recruitment of white blood cells to the follicle.

Propionibacterium acnes (Toyoda, et al)
Propionibacterium acnes (Toyoda, et al)

The initial inflammation of an acne lesion can often cause additional damage to the follicle and surrounding tissue, increase the growth of bacteria and induce further swelling and discomfort. In some individuals, this process becomes a vicious cycle and leads to extensive acne and significant damage to the skin and the subcutaneous matrix that supports healthy skin. Severe and repeated damage that is caused by inflammatory acne lesions can cause permanent acne scars.

Sebum and a Healthy Follicle

Composition of Human Sebum
Composition of Human Sebum

Sebum is a mixture of fatty acids and lipids that is essential for lubricating and protecting healthy skin. Sebum is produced by Sebaceous Glands, which are attached to the base of hair follicles. In a healthy follicle, the sebaceous gland produces the appropriate amount of sebum to maintain the health of the surrounding skin, and that sebum is efficiently extruded along with the hair.

For individuals with acne, several things can happen that disrupt the delicate balance of sebum production. Normal sebaceous glands are relatively small and produce a minimal amount of sebum. However, excessive growth of the sebaceous glands (sebaceous hyperplasia) and overproduction of sebum can be an important contributor to acne symptoms. Sebaceous hyperplasia can be triggered by increases in androgen hormones, which is common for males during puberty.

Sebaceous Glands and Sebum Production (Toth)
Sebaceous Glands and Sebum Production (Toth)

Sebum itself is created by the breakdown of the cells that form the sebaceous gland. Sebaceous cells replicate at the base of the gland and move up towards the hair follicle as the new cells proliferate. As the maturing cells approach the hair follicle, they undergo apoptosis and die. The cells are lipid rich (oil) and the byproducts left over as the cells dissolve composes the sebum that lubricates and protects the hair. Proliferation of the sebaceous glands causes an increase in the production of sebum, which is often manifested as oily skin and hair.

UV Fluorescence of Propionibacterium acnes Bacteria in Nose Pores
UV Fluorescence of Propionibacterium acnes Bacteria in Nose Pores

Sebum can also serve as a nutrition source for bacteria that reside inside the hair follicle, such as P. acnes and S. aureus. Excess amounts of sebum can encourage bacterial growth and lead to inflammation, redness and an infiltration of white blood cells (pus). If a hair follicle is plugged near the surface, this process can often lead to the formulation of a surface pustule (whitehead). However, for many people who suffer with inflammatory acne, the pustules are often formed deep in the tissue and away from the surface. These deep-seated pustules are responsible for nodular and cystic acne symptoms (Acne Types: 3-4).

Type 4 Acne on Face
Type 4 Acne is Likely to Cause Acne Scars

The deep-seated pustules that form in nodular and cystic acne lesions are surrounded by tissue and it is difficult to drain the pus and bacteria to the surface (eg. “pop” or lance the pimple). Individuals with acne lesions that are significantly inflamed or painful should generally avoid trying to “pop” these pimples at home. Effectively and safely draining these lesions can reduce symptoms and accelerate healing, but these procedures should be performed by a trained medical professional. Many times, continued sebum production, bacterial growth and inflammation within a plugged follicle can cause the follicle to rupture and drain into the surrounding tissue. This process can lead to further inflammation, dissemination of the bacterial infection, worsening acne symptoms and the formation of acne scars.

Is acne caused by dirt or not washing my face enough?

Facial Cleansers are Popular OTC Acne Products

Answer: Not really.

Topical facial cleansers are generally ineffective treatments for all but the most mild cases of acne (Acne Type: 1). Medicated and non-medicated acne washes are widely available in grocery, drug and department stores as Over The Counter (OTC) products.

In most acne lesions (pimples, nodules, cysts, etc.), the site where the infection and inflammation is centered is not near the surface of the skin. Instead, it is near the base of the hair follicle where the sebaceous gland attaches. This is a region of the follicle that is not readily accessible from the surface. Therefore, cleansers and their active ingredients are unlikely to impact the inflammatory processes that drive moderate to severe acne symptoms (Acne Types: 2-4).

Topical Face Wash Acne Cleansers
Topical Face Wash Acne Cleansers

Commercials for acne cleansers often have animations that show their product blasting out the debris from deep within pores (follicles). In reality, this does not really happen because the follicle shaft is quite narrow relative to its depth. In addition, individuals with acne often have sticky “hyper-keratinized” plugs that are firmly lodged in the follicle. These plugs prevent surface-applied treatments from reaching the interior of the follicle. The inside of the follicle is mostly an anaerobic environment (low levels of oxygen). The interior of the follicle has a different composition of resident bacteria than the surface of the skin.

The plugs that clog follicles and contribute to acne do not usually come from dirt or grime on the surface of the skin. Rather these pore-clogging plugs come from sebum, keratin and cell debris which is all produced deep within the follicle. Sebum is a natural product of the sebaceous glands and is responsible for lubricating and protecting healthy skin.

Propionibacterium acnes (Toyoda, et al)
Propionibacterium acnes (Toyoda, et al)

It is important to recognize, however, that foreign debris and bacteria on the surface of the skin can aggravate acne symptoms. This is especially true if you pop a pimple or damage the skin, which allows surface debris and bacteria to enter the open wound. This can potentially cause increased inflammation and even a secondary infection, both of which can exacerbate existing acne symptoms.

Cleansers and Acne: The Positives

Salicylic Acid Cleanser Wash (Neutrogena)
Salicylic Acid Cleanser Wash (Neutrogena)

Twice daily use of non-medicated gentle facial cleansers was shown to decrease the number of open-comedos (blackheads) in a small study. However, non-medicated cleansers had no measurable effect on closed comedos and inflammatory acne (whiteheads, nodules, cysts). This is most likely due to the concept mentioned above, that the plug blocking the follicle is not easily accessible from the surface in closed comedo and inflammatory acne lesions.

In the case of a blackhead (open-comedo), the plug is very near the surface of the skin, and is therefore more susceptible to to the action of cleansers. Another study by the same research group showed that a medicated cleanser that contained Triclosan, Salicylic Acid and Azelaic Acid (antibacterial and keratolytic agents) was capable of decreasing the number of acne lesions when compared to a non-medicated control.

Salicylic Acid Cleanser Pads (AcneFree)
Salicylic Acid Cleanser Pads (AcneFree)

Triclosan, Salicylic Acid and Benzoyl Peroxide are common ingredients in Over The Counter (OTC) acne treatments. The available research indicates that when cleansers are used in moderation they can be helpful in reducing minor acne symptoms for some patients.

It is important to note that most of the OTC medications have the same ingredients, and many acne sufferers use several of these products at the same time. This can easily lead to excessive use of this class of acne product. The most common result of overuse of these products is dry and irritated skin. The positive effects of keratolytic agents and mild anti-bacterial compounds like triclosan are not cumulative and excessive use is likely to lead to more damage than benefit.

Cleansers and Acne: The Negatives

The primary concern associated with acne face and body washes is overuse. When you have acne, you want to do something about it. That’s a natural response, but all too often that desire to act translates into an over-kill approach, like excessive face washing. Most of the research studies on acne and acne facial/body cleanses found that using these products more than twice a day causes more harm than benefit.

Excessive use of acne washes can leave your skin dry, cracked and irritated.
Excessive use of acne washes can leave your skin dry, cracked and irritated.

Excessive use of cleansers or other abrasive products the skin is likely to aggravate acne symptoms. Excessive washing or use of harsh products can damage and irritate the skin, leading to cracking, redness, inflammation, discomfort and ultimately worsen acne symptoms. The general rule of thumb is to use gentle cleanser in moderation to keep the skin clean. Washing the skin more than that is unlikely to provide much benefit and is more likely to make symptoms worse.

It is also important to limit your expectations for how helpful cleansers and face washing are going to be for your acne. Keep in mind that even the studies that show that cleansers help acne are only talking about moderate improvements for people with mild acne.

Overall, the consensus of scientific research does not suggest that cleansers help moderate to severe inflammatory acne. At no point do any of these research results indicate that cleansers can “cure” acne. At best, cleansers can only be expected to marginally improve acne symptoms.

References and Sources

How to Wash Your Face: America’s Leading Dermatologist Reveals the Essential Secrets for Youthful, Radiant Skin. Kenet, et al. 2002.
A Consumer’s Dictionary of Cosmetic Ingredients, 7th Edition: Complete Information About the Harmful and Desirable Ingredients Found in Cosmetics and Cosmeceuticals. Winter. 2009.
Acne Vulgaris. Shalita, et al. 2011.
A systematic review of the evidence for myths and misconceptions in acne management: diet, face-washing and sunlight. Magin, et al. 2004.
A Single-Blinded, Randomized, Controlled Clinical Trial Evaluating the Effect of Face Washing on Acne Vulgaris. Choi, et al. 2006.
A study of the efficacy of cleansers for acne vulgaris. Choi, et al. 2010.

Is Acne Different Between Men and Women?

Acne Tends to be Different Between Men and Women

Yes, and it mostly comes down to hormones.

Men and women tend to experience acne differently. Men are more likely to develop acne during puberty and are more likely to develop severe and inflammatory forms of the disease. Acne symptoms tend to peak during adolescence and recede during a male’s mid 20’s. In contrast, women tend to experience less acne and less severe acne than men, but rates of acne actually increase for women in the 20-40 age range. Many women who have never had complexion problems begin to experience acne symptoms during pregnancy, and sometimes acne continues to persist after completion of the pregnancy.

Androgens Drive Muscle Growth
Androgen Hormones Drive Muscle and Body Hair Growth

While there are many contributing factors to acne, the main differences between men and women can be traced to hormones. Men, particularly adolescent males, tend to have elevated levels of male hormones called androgens. Androgens include hormones like testosterone. Among other things, androgens stimulate the growth of sebaceous glands, which increases the amount of sebum produced by the skin. Increased sebum production fosters the growth of bacteria that feed on sebum, such as Propionibacterium acnes. Additionally, high levels of sebum production can increase the incidence of clogged pores that block the opening of the hair follicle and encourage the development of acne symptoms like pimples, nodules and cysts.

Androgen Inhibitors and Acne

Finasteride 5mg Tablets (Fincar)
Finasteride is an Androgen Inhibitor

Androgen Inhibitors are a class of medication designed to block the function of endogenous androgens. Androgen Inhibitors are commonly used in women to treat elevated androgen levels, which can lead to hirsutism (excess hair growth) and masculinization. They are also used in men to treat male pattern baldness and certain kinds of cancer.

Androgen Inhibitors can be an effective treatment for women who experience androgen-dependent acne. Androgen inhibitors have a feminizing effect on men and are generally not recommended for use in males. Androgen inhibitors are often used as part of the hormone therapy involved in male to female sex change operations.

References

Correlation Between Serum Levels of Insulin-like Growth Factor 1, Dehydroepiandrosterone Sulfate, and Dihydrotestosterone and Acne Lesion Counts in Adult Women. Cappel, et al. 2005.
Acne in Victorian adolescents: Associations with age, gender, puberty and psychiatric symptoms. Kilkenny, et al. 1997.
Post-adolescent acne: a review of clinical features. Goulden, et al. 1997.
Prevalence of facial acne in adults. Goulden, et al. 1999.

The Antibacterial Activity of Essential Oil

Eucalyptus Essential Oil Vials

Many essential oils and other plant extracts have antimicrobial properties which can be helpful for health and wellness applications. There is an incredible diversity of essential oils and other plant extracts available on the market today. This selection provides a plethora of options for both professional and casual practitioners of Naturopathic remedies for many health issues, including acne.

Antimicrobial Properties of Essential Oil

Clove Flowers
Clove Flowers

Much of what makes up an essential oil are molecules which are part of a plant’s natural defense system. These molecules have been designed by millions of years of evolution to protect the plant against potential enemies. These enemies can be bacteria, fungi, viruses, other plants, insects and other animal predators.

Some components of essential oil have antibacterial, anti-viral and anti-fungal activity. Other components in the essential oil are designed to prevent predation by insects and other animals. Some essential oils may even be toxic to other plants and are designed to help inhibit the growth of competing plants.

In the last twenty years, a great deal of scientific research has been done to characterize the antimicrobial activity of many essential oils. Using this knowledge can help guide better decisions when designing effective Naturopathic treatments for acne.

The Antibacterial Activity of an Essential Oil Depends on the Species of Bacteria

Some essential oils are highly toxic to certain species of bacteria, but are harmless to others. While some essential oils are effective against a broad spectrum of different bacteria, others are only useful against very specific types of bacteria.

Propionibacterium acnes (Toyoda, et al)
Propionibacterium acnes (Toyoda, et al)

When designing a Naturopathic acne treatment that includes essential oils, it is important to be aware of these differences. To better improve the design of acne treatments, we have compiled scientific reports from many sources in order to help identify which essential oils are likely to be most effective against acne-causing bacteria, such as Propionibacterium acnes (P. acnes) and Staphylococcus aureus (S. aureus).

Many essential oils also have anti-inflammatory properties which may  also help in the treatment of acne symptoms.

What Essential Oils are Effective Against Propionibacterium acnes Bacteria?

Tea Tree Flowers
Tea Tree Flowers

Scientific research reports indicate that there are many types of essential oil that are active against P. acnes bacteria. Tea Tree essential oil is one of the most popular essential oils for skin care applications, and the research shows that it is indeed toxic to P. acnes bacteria (although not as much as some other essential oils). Thyme, Clove and Cinnamon essential oil have broad spectrum antibacterial properties, and are also effective against P. acnes as well.

Unfortunately, many of the essential oils with significant antibacterial activity against P. acnes bacteria can also be fairly irritating to the skin, particularly at higher concentrations. However, there are several essential oils which have excellent antibacterial properties and a lower risk of skin irritation. For example, several different kinds of Citrus essential oils, were highly toxic to P. acnes bacteria but tend to be fairly mild to the skin. Lemongrass essential oil is another a potentially useful option for acne treatments.

Antibacterial Activity of Essential Oil Against Other Bacterial and Fungal Infections

There have been many research studies which examine the ability of different essential oils to inhibit or kill different kinds of infectious bacteria and fungi. No matter what kind of application you have in mind – whether it is designing a Naturopathic acne treatment or developing a natural disinfectant – understanding the antimicrobial properties of different essential oils is a critical first step. To help improve the understanding of these properties, we are working on developing a comprehensive database that about essential oils and their antimicrobial activities.

Selected Results from Research Studies on the Antibacterial Activity of Essential Oils

Minimum Inhibitory Concentrations of Many Essential Oils Against 5 Strains of Propionibacterium acnes (Luangnarumitchai)
Minimum Inhibitory Concentrations of Many Essential Oils Against 5 Strains of Propionibacterium acnes (Luangnarumitchai)
Inhibition of Propionibacterium acnes Growth by 10 Essential Oils (Zu)
Inhibition of Propionibacterium acnes Growth by 10 Essential Oils (Zu)
Antimicrobial Activity of 21 Essential Oils Against Propionibacterium acnes and Other Bacteria (Prabuseenivasan)
Antimicrobial Activity of 21 Essential Oils Against Propionibacterium acnes and Other Bacteria (Prabuseenivasan)
Antibacterial Activity of Many Essential Oils Against 10 Species of Bacteria (Hammer)
Antibacterial Activity of Many Essential Oils Against 10 Species of Bacteria (Hammer)

References

Activities of Ten Essential Oils towards Propionibacterium acnes and PC-3, A-549 and MCF-7 Cancer Cells. Zu, et al. 2010.
Antimicrobial Activity of Essential Oils Against Five Strains of Propionibacterium acnes. Luangnarumitchai, et al. 2007.
Antimicrobial activity of essential oils and other plant extracts. Hammer, et al. 1999.
Antioxidant Activities and Volatile Constituents of Various Essential Oils. Wei, et al. 2007.

Is Popping a Pimple a Bad Idea?

Whitehead Pimple

Answer: It can be, especially if done improperly.

Popping a Pimple
Popping a Pimple

Some pimples and other acne lesions benefit from being drained or popped in order to remove pus and accelerate healing, but other pimples should be left alone to heal on their own. The nodules and cysts of those patients who suffer from severe inflammatory acne (Acne Type: 4) are often lanced and drained by a dermatologist. This can prevent further damage and limit post-acne scarring.

The important thing is to identify those zits and pimples which can be effectively popped (and which ones can not), and to do that properly and in a sterile fashion. Although it can be tempting to try and pop all zits pimples, in many cases it is more effective to allow the natural progression of the lesion and healing process to take place.

Benefits of Popping a Pimple

Whitehead Pimple Skin and Cellular View
Whitehead Pimple Skin and Cellular View

In some cases, it can be beneficial to extract the pus from inside of a pimple. Pus (the white stuff, not the clear fluid) is composed largely of specialized white blood cells called Neutrophils. These white blood cells migrate to the site of infection (the zit) and are designed to destroy and phagocytose (eat) the offending bacteria and other foreign material. These white blood cells are most apparent in open comedome lesions (whitehead pimples).

After accumulating in an acne lesion, the white blood cells release powerful enzymes and free radicals that are designed to kill and digest the source of infection. Unfortunately, these weapons also cause collateral damage to the healthy tissue around the infected follicle. In people who suffer from inflammatory acne, it is often an overeager immune response that causes swelling, redness and discomfort. The collateral damage to healthy tissue during this process is what causes the formation of acne scars.

In acne lesions that are significantly inflamed but easy to drain, removing the pus can limit the amount of collateral damage that occurs and can accelerate the healing process. In addition, the infiltration of the follicle with pus can put a lot of pressure on the surrounding nerves, which can be quite uncomfortable and painful. Draining a lesion may be helpful in relieving this pressure and the accompanying discomfort.

Risks of Popping a Pimple

Corticosteroid Injection into Acne Cyst
This Acne Cyst Requires Surgical Extraction

Many acne lesions (especially nodular and cystic acne lesions) can be very difficult to effectively pop and drain. Small, non-inflammatory acne lesions (Acne Types: 1-2) may not contain significant pus that can be drained. In these cases, attempting to drain the lesion can be unhelpful or cause further damage that slows down the healing process and contributes to more acne scarring.

In many acne pimples and cysts it is not just that the follicle is swollen with white blood cells and edema fluid, but rather the entire region of skin tissue is affected. Channels can form in the sub-cutaneous tissue and these channels can be occupied by bacteria laden white blood cells. Non-productive squeezing of pimples in these cases can force these white blood cells (and bacteria) away from the pimple and into the surrounding tissue. This can further spread the underlying infection and inflammation.

Aggressive squeezing of pimples can cause additional damage to the follicle itself, which leads to more inflammation and extends the amount of time it takes for the damage to be repaired. Lancing or popping an acne lesion in a non-sterile fashion can introduce bacteria or foreign material that can lead to more inflammation or even a secondary infection.

In conclusion, there are a lot of things that can go wrong when popping a pimple. Most of these are related to improperly draining a lesion or attempting to drain an unsuitable lesion, or non-sterile technique.

Considerations for Popping a Pimple

Sterility

Neosporin Ointment
Neosporin Ointment

It is very important to sterilize the area to be treated both before and after attempting to extract a blackhead or drain a pimple. This includes thoroughly washing your hands, cleaning the treated area and swabbing the lesion with alcohol or medicated wipe before and after extraction/draining. Topical application of Neosporin can also be used to limit the chances of secondary infection and accelerate healing.

Selecting Appropriate Pimples

It is going to do more harm than good if you try to pop a pimple that is not ready or is not suitable for draining. For example, many whiteheads are good candidates for drainage because the infiltrate (pus) is pooled near the surface. However, many inflammatory acne lesions, like nodules and cysts are poor candidates for drainage because there is no easy way for the infiiltrate to reach the surface.

In acne lesions where you have inflamed red bumps, like nodules and cysts, the infiltrate is fairly deep under the surface of the skin, with no clear exit pathway. In these cases of inflammatory acne, the entire length of follicle above the epicenter of the lesion is likely to be inflamed, and basically swollen shut. Attempting to squeeze or drain these type of lesions often forces the infiltrate (which contains many inflammatory factors) down and out, into the surrounding tissue. This will most likely aggravate the situation, causing more inflammation, scarring and a lengthier healing process.

In general, to effectively drain an inflammatory acne cyst or nodule, they often must be surgically lanced, which is a procedure best done in a dermatology clinic.

Proper Technique

Whitehead Removal with Comedome Extractor
Whitehead Removal with Comedome Extractor

To extract a blackhead, or drain a whitehead, it is important to use good technique. This means applying gentle pressure in a manner that forces the plug or infiltrate up and out. To do this you need to try and get under the main pocket of the lesion and gently work it out. It is important to use gentle rolling pressure.

Vigorous squeezing and applying lots of pressure are much more likely to cause additional damage and aggravate the acne lesion. There are several manual “extractors” used to extract blackheads. These generally have a small ring that fits around the blackhead and are designed to apply even pressure around the follicle. However, research studies into these blackhead extractions show that they produce, at best, a mild improvement compared to doing nothing.

Some dermatologists use a machine that extracts hyperkeratinic plugs and other follicle plugs using a suction based extraction machine. For the casual, at-home user, pore strips offer a means to extract some easily accessible blackheads, but pore strips are not suitable for inflamed lesions (eg. whitehead pimples).

Example Technique

Anabolic Steroids and Acne

Muscles and Epigenetic Adaptation

What are Anabolic Steroids?

Arnold Used Lots of Anabolic Steroids
Arnold Used Lots of Anabolic Steroids

Anabolic Steroids (aka Roids, Juice, AAS, etc) are molecules that mimic the shape and function of androgen hormones (eg. Testosterone). Anabolic Steroids are generally used to stimulate protein synthesis and muscle growth.

Anabolic steroids should not be confused with corticosteroids, which are immune suppressants and can actually inhibit muscle growth. Corticosteroid injections are sometimes used to treat acute inflammation in severe acne lesions. Anabolic Steroids are never used as an acne treatment, and their use can cause or worsen acne symptoms.

There are numerous medical conditions for which Anabolic Steroids are legitimately used as treatments, but Anabolic Steroids are better known for their use as performance enhancing drugs. Virtually all major sporting leagues ban the use of Anabolic Steroids, although this doesn’t necessarily prevent their use by athletes. Anabolic Steroids use by individuals for aesthetic purposes is also common in some populations.

Risks and Side Effects of Anabolic Steroid Use

There is widespread concern and controversy about the danger posed by both aesthetic and performance enhancing use of Anabolic Steroids. While some of the danger may be overstated, there are many well-known side effects associated with the use of Anabolic Steroids, including: Growth disruption in adolescents, hormone balance problems, accelerated male pattern balding, cardiovascular problems, contaminated/counterfeit medications, psychological problems (e.g. roid rage) and acne vulgaris.

Androgens Drive Muscle Growth
Androgen Hormones Drive Muscle and Body Hais Growth

Research shows that negative side effects of Anabolic Steroid use tend to occur in a dose dependent fashion. Higher and more frequent dosing of Anabolic Steroids is generally associated more frequent and severe side effects. The side effect profile is also dependent on the precise type of Anabolic Steroid being used. With the rapid expansion in designer Anabolic Steroids over the last two decades, a tremendous diversity of options now exists in the marketplace.

How Anabolic Steroids Work

Testosterone is an Androgen Hormone
Testosterone is an Androgen Hormone

Androgens are the primary hormones responsible for many of the masculine characteristics that differentiate males and females. While females naturally produce androgen hormones like testosterone, they tend to produce much less than males. Anabolic Steroids are usually compounds that are structurally similar to the testosterone.

Focused scientific development of Anabolic Steroids was pioneered by the Soviet Union to improve their competitiveness in international athletic competitions (e.g. the Olympics. The first Anabolic Steroids were simple blends of testosterone and its naturally occurring derivatives. However, these first generation steroids not only increased muscle growth but also had potent masculinizing effects on the user. These effects were most evident in female athletes, with the women of the East German Olympic teams of the 1970’s and early 80’s being the most famous examples. Starting in the 1970’s doctors and scientists began researching new testosterone derivatives that would encourage muscle growth with fewer side effects, so called “designer steroids”.

Many of the cells that compose the human body have sensors called “androgen receptors” that mediate cellular responses to androgen hormones. When the androgen hormone is detected by the cell it stimulates changes in gene expression and metabolism in the cell. However, not all cells respond the same way when they are activated by an androgen hormone. Whereas muscle cells may be stimulated to grow and multiply, other cells, like those in the testes, may actually slow their growth.

Diagram of how Molecular Modifications Affect Anabolic vs Androgenic Profile
Diagram of how Molecular Modifications Affect Anabolic vs Androgenic Profile

Androgen receptors are not exactly the same from cell to cell. There are slight differences between the androgen receptors (and their downstream signalling pathways) depending on the type of cell.  The androgen receptors on certain have a high affinity for some androgen hormone derivatives, but a low affinity for others. Over the last thirty years, scientists have been working to develop “designer steroids” that preferentially stimulate the androgen receptors on muscle cells. Significant progress has been made in this pursuit, and today’s designer steroids have far fewer androgenic side effects than those used by the Soviet Union thirty years ago. That said, virtually all Anabolic Steroids still have some level of negative side effects.

Anabolic Steroids and Acne

One of the most common side effects of Anabolic Steroid use is the development of acne on the face, chest and back. The development of acne symptoms is generally caused by the increased activity of the sebaceous glands in response to elevated levels of androgen hormones. High concentrations of androgens (eg. Testosterone) in the body can increase the size and growth rate of the sebaceous glands.

Effect of DHT Androgen on Sebaceous Gland Activity (Akamatsu)
Effect of DHT Androgen on Sebaceous Gland Activity (Akamatsu)

The increase in sebaceous gland activity generally leads to a corresponding increase in sebum production. High levels of sebum production can increase the incidence of clogged pores and induce the growth of acne-causing bacteria, such as Propionibacterium acnes. P. acnes bacteria use sebum as a nutritional source. Increased sebum levels can also contribute to increased inflammation in and around the follicle, worsening acne symptoms, contributing to tissue damage and increasing the risk of acne scarring.

Different types of designer Anabolic Steroids have different profiles of androgenic side effects. Anabolic steroids like testosterone and dihydrotestosterone have a relatively high androgenic to anabolic (muscle building) profile, while some synthetics like Oxandrolone tend to have fewer androgenic side effects, relative to the dose.

Sebaceous gland activity is not only regulated by androgens, but also by other compounds that may be used in “performance enhancement” applications. For example, Human Growth Hormone (hGH) is a commonly used muscle building supplement that can also potentially contribute to acne symptoms. Human growth hormone stimulates the production of another growth factor Insulin-Like Growth Factor 1 (IGF-1) which has also been shown to increase sebaceous gland activity.

There are a lot of variables and cross-reacting factors when it comes to Anabolic Steroids and their side effects, like acne. As always, it is strongly recommended that any steroid therapy be done under the supervision of a qualified medical professional. Illicit steroid use can be quite dangerous not only because of the known side effects and legal restrictions (in many countries), but also because of the high incidence rate of poorly labeled, impure and counterfeit product being sold as Anabolic Steroids in the unregulated market.

Treatment of Anabolic Steroid Induced Acne

Obviously, stopping the use of Anabolic Steroids is one solution, although maybe not realistic in all cases. Additionally, stopping use might not actually be enough to completely resolve acne symptoms that were caused by prior Anabolic Steroid use. In most cases of acne (steroid-induced acne included), a central feature of acne is a persistent infection of P. acnes bacteria within hair follicle. Once established, this infection may persist for long after steroid use is stopped. Fortunately, individuals with steroid related acne have many treatment options available to them, including:

RETINOIDS

Isotretinoin Roaccutane Packaging
Isotretinoin (Roaccutane, Accutane)

Both oral retinoids and topical retinoids can help decrease sebaceous gland activity and improve acne symptoms in many individuals. However, there is some research that indicates that oral retinoids (Accutane) may negatively impact athletic performance and recovery times. As a result, oral retinoids are rarely prescribed to competitive athletes who are in active competition. Topical retinoids are effective in some cases, but they tend to be less effective against inflammatory, nodular and cystic forms of acne. Unfortunately, inflammatory acne is fairly common with steroid use.

ANTIBIOTICS

Tetracycline Antibiotic Capsules
Tetracycline Antibiotic Capsules

There are a wide range of topical and oral antibiotics that have been shown to be viable anti-acne treatments. Like topical retinoids, topical antibiotics usually have reduced efficacy against inflammatory forms of acne. Some oral antibiotics have been shown to have both antibacterial and anti-inflammatory properties.

ANDROGEN INHIBITORS

Finasteride Tablets (Propecia)
Finasteride Tablets (Propecia)

While it is unlikely that an individual who is using Anabolic Steroids would be interested in using a systemic androgen inhibitor, there are some topical androgen inhibitors available which have a minimal systemic impact. These topical androgen inhibitors have been used to decrease the effect of anabolic steroids on the skin in a targeted fashion. However, there is not much research on this approach and minimal evidence about its efficacy.

OVER THE COUNTER MEDICATIONS

Over The Counter (OTC) Acne Products
Over The Counter (OTC) Acne Products

For mild cases of steroid induced acne, Over The Counter (OTC) medications that contain benzoyl peroxide, salicylic acid and other antibacterial/keratolytic compounds may be helpful in improving acne symptoms. These medications are generally most effective with mild, non-inflammatory (Acne Types: 1-2) and are less effective against moderate and severe acne symptoms (Acne Types: 3-4).

Common Anabolic Steroids and Their Chemical Structures

Commonly Androgenic Steroids
Common Anabolic Steroids
Chemical Structures of Common Anabolic Steroids (Fragkaki)
Chemical Structures of Common Anabolic Steroids (Fragkaki)

References

A league of their own: demographics, motivations and patterns of use of 1,955 male adult non-medical anabolic steroid users in the United States. Cohen, et al. 2007.
Adverse health effects of anabolic androgenic steroids. Amsterdam, et al. 2010.
Anabolic steroid abuse: Psychiatric and physical costs. Talih, et al. 2007.
Pharmacology of anabolic steroids. Kicman. 2008. 
Social capital: Implications from an investigation of illegal anabolic  steroid networks. Maycock, et al. 2007.
Structural characteristics of anabolic androgenic steroids contributing to binding to the androgen receptor and to their anabolic and androgenic activities: Applied modifications in the steroidal structure. Fragkaki, et al. 2009. 
Control of Human Sebocyte Proliferation in Vitro by Testosterone and 5-DHT is Dependent on the Localization of the Sebaceous Glands. Akamatsu, et al. 1992.