Finasteride vs. Spironolactone

See how Finasteride and Spironolactone compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Finasteride is FDA-approved for male pattern hair loss and BPH in men, while spironolactone's use for hair loss is entirely off-label.

  • Spironolactone is mainly used off-label for female pattern hair loss, hirsutism, and acne, since it is FDA-approved only for blood pressure, heart failure, and fluid retention.

  • Finasteride's main side effects involve sexual function, while spironolactone's main side effects involve hormone-related changes like menstrual irregularity and breast tenderness.

Finasteride vs. Spironolactone Drug Summary

Finasteride

Finasteride is a 5-alpha-reductase inhibitor FDA-approved to treat male pattern hair loss and benign prostatic hyperplasia (BPH) in men. It comes as a once-daily oral tablet, with a 1 mg dose used for hair loss and a 5 mg dose used for BPH.

Spironolactone

Spironolactone is a potassium-sparing diuretic and androgen blocker FDA-approved for high blood pressure, heart failure, and fluid retention. It is taken as a once-daily oral tablet, and dermatologists also prescribe it off-label for female pattern hair loss, hirsutism, and acne.

Finasteride vs. Spironolactone Side Effects

Finasteride

Most common
Decreased libido (up to 1.8%)
Erectile dysfunction (up to 1.3%)
Decreased ejaculate volume (up to 1.2%)
Ejaculation disorder (up to 1.2%)

Spironolactone

Most common
Menstrual irregularities (up to 30%)
Gynecomastia (up to 10%)
Dizziness (up to 4%)
Hyperkalemia (up to 3%)

Finasteride vs. Spironolactone Dosage

Finasteride

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 1 mg once daily At the start
Maximum dose 5 mg once daily If needed
Dose changes 1 increase As tolerated

Spironolactone

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 50 mg once daily Weeks 1-2
Maximum dose 100-200 mg once daily If needed
Dose changes 2 increases As tolerated

Finasteride vs. Spironolactone Indications

Finasteride

Finasteride is FDA-approved to treat androgenetic alopecia (pattern hair loss) in men and to shrink an enlarged prostate in men with BPH. It works by blocking the conversion of testosterone to DHT, the hormone most responsible for hair follicle shrinkage and prostate growth. It is also used off-label to treat hirsutism in women with excess androgen levels.

  • Male pattern hair loss (androgenetic alopecia) in men - FDA-approved

  • Benign prostatic hyperplasia (enlarged prostate) in men - FDA-approved

  • Hirsutism in women with excess androgens - off-label

  • Not approved for use in women or in children

Spironolactone

Spironolactone is FDA-approved for high blood pressure, heart failure, and fluid buildup caused by heart, liver, or kidney disease, and to help diagnose and treat primary hyperaldosteronism. It is not FDA-approved for hair loss, but dermatologists commonly prescribe it off-label to treat female pattern hair loss along with hirsutism and hormonal acne.

  • Heart failure (NYHA class III-IV) - FDA-approved

  • Resistant hypertension, as add-on therapy - FDA-approved

  • Edema from heart, liver, or kidney disease - FDA-approved

  • Female pattern hair loss, hirsutism, acne - off-label

Finasteride vs. Spironolactone Pros and Cons

Finasteride

Finasteride has a long track record specifically for male hair loss, with FDA approval since 1992 and decades of trial data behind it. Coverage for the hair loss indication is often out-of-pocket since insurers tend to treat it as cosmetic.

Pros

  • FDA-approved specifically for male pattern hair loss, backed by large trials

  • Once-daily pill with more than 30 years of established safety data

  • Targets DHT directly with minimal effect on blood pressure or electrolytes

  • Widely available as a low-cost generic tablet

Cons

  • Only approved for use in men; women who are or may become pregnant should not handle it

  • Sexual side effects like low libido can persist after stopping the drug

  • Does not treat hirsutism or acne the way spironolactone can

  • Can lower PSA levels, which may complicate prostate cancer screening

Spironolactone

Spironolactone brings decades of cardiovascular safety data to an off-label role in hair loss, making it a familiar option for prescribers despite lacking approval for that use. Insurance usually covers it readily for its approved indications, though coverage specifically for hair loss can vary.

Pros

  • Off-label option for female pattern hair loss that also treats hirsutism and acne

  • More than 60 years of clinical use, mostly for blood pressure and heart failure

  • Flexible tablet strengths allow gradual dose titration to balance effect and tolerability

  • Can be paired with oral contraceptives to manage menstrual side effects

Cons

  • Not FDA-approved for any form of hair loss; all hair-related use is off-label

  • Requires periodic blood tests to check potassium and kidney function

  • Menstrual irregularities are common at the doses used for hair loss

  • Breast tenderness and other feminizing effects make it unsuitable for most men

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