Spironolactone in the treatment of acne functions as both an androgen receptor blocker and possibly also an inhibitor of 5 alpha-reductase type 1. In doses of 50 to 100 mg per day, it has been shown to reduce sebum production and improve acne.
Spironolactone may be used for female patients with therapy-resistant acne, although it has not been formally approved for this condition.
In one study looking at spironolactone in the treatment of acne, one third of the patients had complete clearing of their acne. One third showed marked improvement, and nearly one third showed partial improvement, with less than 10% showing no improvement of their acne.
Spironolactone side effects for women are increased at higher doses and include the potential for increased potassium in the blood, a slight lowering of the blood pressure, irregular menstrual periods, breast tenderness and enlargement, headache, and fatigue.
The increased potassium in the blood is rare in healthy young women. Although breast tumors have been reported in rats treated with spironolactone, this drug has been used for years in human and has not been directly linked with the development of cancer in more than 30 years of spironolactone usage.
As spironolactone is an antiandrogen, there is a risk of feminization of a male fetus if a pregnant woman takes this medication. The risk to a fetus and the symptoms of irregular menstrual periods can be improved by combining the treatment with an oral contraceptive.
Spironolactone side effects for acne can be minimized if treatment is started at a low dose of 25 mg per day and increased every few months as needed because the response can take as long as 3 months, as with other hormonal therapies. Once adequate response is attained, dosage can again be lowered to the minimal dose required to maintain adequate results.