Cimetidine (Tagamet) is a medication that is used primarily to treat heartburn and peptic ulcers, but also functions as a weak Androgen Inhibitor.

Cimetidine is a histamine H2 receptor antagonist that was once among the most commonly used medications to treat heartburn, but has since been largely replaced by newer medications with fewer side effects. Cimetidine is rarely used as a treatment for acne.

Cimetidine has been shown to be a weak Androgen Inhibitor in several research studies. Cimetidine can block the activity of the androgen hormones testosterone and dihydrotestosterone (DHT), particularly at higher dosages. Cimetidine has also been shown to increase levels of the female hormone estrogen.

Cimetidine was tested as both an oral and topical treatment for acne in several clinical research studies. Treatment with Cimetidine was found to improve acne symptoms a little bit in some patients, but Cimetidine was generally less effective for treating acne than other Androgen Inhibitors (eg. Spironolactone).

Androgen hormones stimulate the growth and activity of the sebaceous glands and production of sebum. Excessive sebaceous gland activity can contribute to acne symptoms. Androgen Inhibitors such as Cimetidine may help improve acne symptoms by reducing the effects of elevated androgen levels.

Oral formulations of Cimetidine are available as Over-The-Counter (OTC) medications for the treatment of heartburn.