Imiquimod is an immune response modifier used topically to treat certain skin conditions, including external genital and perianal warts, superficial basal cell carcinoma, and actinic keratosis. It works by stimulating the innate immune system through activation of toll-like receptor 7 (TLR7), leading to the production of cytokines such as interferon-α that help the body recognize and destroy abnormal or virus-infected cells. Imiquimod was developed in the late 1980s and early 1990s by 3M Pharmaceuticals during research into antiviral and antitumor agents, initially being investigated for its interferon-inducing properties. It was first approved for medical use in the United States in 1997 for the treatment of external genital warts and later expanded to other dermatological indications in the early 2000s as its immunomodulatory potential became better understood.
