Cimetidine can treat skin diseases. Cimetidine is a blocker of H2 receptors and has anti-allergic effects, so it is usually used to treat acute and chronic urticaria. The oral dose is 0.2 grams per dose, 3 times a day, or it can be given intramuscularly or intravenously at 0.2-0.4 grams per dose, 1-2 times a day. Precautions are that adverse reactions such as anaphylaxis, elevated serum transaminases, and acute interstitial nephritis can occasionally occur, but such occurrences are rare. Cimetidine also has a mild anti-androgenic effect, so it can be used in dermatology to treat acne vulgaris and seborrheic alopecia, because both acne vulgaris and seborrheic alopecia are related to high androgen levels, so oral administration of cimetidine has a suppressive effect on androgens and can treat acne vulgaris and seborrheic alopecia.