Spironolactone is a prescription anti-androgen used off-label for female pattern hair loss, and its side effects are mostly predictable and dose-related — increased urination, menstrual changes, breast tenderness, and dizziness. But one matters more than the rest: it can raise potassium, which is why it needs medical supervision. It's not used for male pattern hair loss because its anti-androgen action can cause feminizing effects in men.
Why spironolactone is used for hair loss
Spironolactone started life as a potassium-sparing diuretic and blood-pressure medication. The reason it shows up in hair loss treatment is a side effect of how it works: it blocks androgen receptors and reduces the effect of testosterone. For women whose thinning is driven by androgens — including many cases of female pattern hair loss and PCOS-related shedding — that anti-androgen action can slow loss and support regrowth.
Common side effects
Most side effects are dose-related and tend to settle as the body adjusts. The ones reported most often include:
- Increased urination, especially early on (it's a diuretic)
- Menstrual irregularities or spotting
- Breast tenderness or enlargement
- Dizziness or lightheadedness from slightly lower blood pressure
- Fatigue and increased thirst
Who shouldn't take it
- Anyone who is or may become pregnant — it can affect a developing male fetus
- People with significant kidney impairment or already-high potassium
- Those on certain blood-pressure drugs (ACE inhibitors, ARBs) without close monitoring
- Men seeking hair loss treatment, due to feminizing effects
What to expect and how it's monitored
Doctors typically start at a low dose and increase gradually. Hair results take 3–6 months or more to appear, and treatment is ongoing. Periodic blood-pressure and sometimes potassium checks are normal. Spironolactone is often paired with a reliable form of contraception — both to prevent pregnancy and, in some cases, for added anti-androgen benefit.
Exploring treatment for female hair loss?
Some online clinics evaluate and prescribe options like spironolactone after a consult.
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Written by
Daniel Reyes
Editor-in-Chief, Happy Hair Journey
Daniel has spent five years researching men's hair loss treatments and personally testing protocols across minoxidil, microneedling, and LLLT. He reviews every published study referenced on this site.
Medically reviewed by
Dr. Maya Chen, MD
Board-certified dermatologist · NYU Langone