Nalidixic Acid (Wintomylon) is an antibiotic in the Quinolone family. It is primarily used to treat certain infections caused by gram-negative bacteria.
Nalidixic Acid is rarely used as an acne treatment. Nalidixic Acid has weak antibacterial against most gram-positive bacteria, which includes the acne-causing P. acnes bacterium. Laboratory testing indicates that many strains of P. acnes bacteria are highly resistant to Nalidixic Acid. There is little clinical research and few patient reports about the efficacy of Nalidixic Acid as a treatment for acne.