Spironolactone for hirsutism

Spironolactone acts in various ways in hirsutism; it is a mineralocorticoid antagonist, an androgen receptor antagonist at the hair follicle, and a weak 5-alpha-reductase inhibitor. It also has a weak progestogenic effect and, if used alone, can lead to irregular uterine bleeding or amenorrhoea; ideally, it should be used in combination with a COC to avoid this.

A typical regimen is:

Spironolactone can cause hyperkalaemia, particularly in patients with kidney impairment, and those taking angiotensin converting enzyme inhibitors (ACEI) or angiotensin II receptor blockers (ARB). Consider assessing kidney function and serum potassium concentration before starting therapy and monitor periodically. Advise patients to avoid potassium supplements while taking spironolactone.

Spironolactone is well tolerated, but polyuria and postural hypotension may occur at the start of treatment; consider reducing dose to 50 mg if these effects occur.