Ketoconazole Products | Cleanchem - Ketoconazole is an antifungal medication that inhibits ergosterol synthesis, a key component of fungal cell membranes. It is used topically for treating fungal skin infections and seborrheic dermatitis, and orally for systemic fungal infections (although oral use is now limited due to liver toxicity concerns). Ketoconazole is also sometimes used off-label for conditions involving excessive androgen production, such as Cushing's syndrome.