Propecia vs. Spironolactone

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

Key Takeaways

  • Propecia is FDA-approved only for male pattern hair loss and works by blocking the conversion of testosterone into DHT with one 1 mg tablet a day.

  • Spironolactone has no FDA approval for hair loss; dermatologists prescribe it off-label for female pattern hair loss because it blocks androgen receptors.

  • Propecia is not safe for women to use or even handle, while spironolactone is rarely given to men because it can cause breast enlargement and low libido.

Propecia vs. Spironolactone Drug Summary

Propecia

Propecia (finasteride) is a 5-alpha-reductase inhibitor taken as one 1 mg tablet a day. It is FDA-approved only to treat male pattern hair loss (androgenetic alopecia) in men, working by lowering scalp DHT, the hormone that shrinks hair follicles.

Spironolactone

Spironolactone is a potassium-sparing diuretic and antiandrogen approved by the FDA for heart failure, high blood pressure, and fluid retention. Dermatologists prescribe it off-label, typically 50 to 200 mg a day, to treat female pattern hair loss by blocking androgen receptors at the follicle.

Propecia vs. Spironolactone Side Effects

Propecia

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%)

Spironolactone

Most common
menstrual irregularities (up to 30%)
dizziness (up to 15%)
gynecomastia (up to 9%)
hyperkalemia (up to 2%)

Propecia vs. Spironolactone Dosage

Propecia

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 1 mg once daily At the start
Maximum dose 1 mg once daily Same as starting
Dose changes None Fixed dose

Spironolactone

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 25-50 mg once daily At the start
Maximum dose 100-200 mg daily If needed
Dose changes 2 increases As tolerated

Propecia vs. Spironolactone Indications

Propecia

Propecia is FDA-approved to treat male pattern hair loss, also called androgenetic alopecia, in adult men. It works by blocking the enzyme that converts testosterone into DHT, the hormone responsible for shrinking hair follicles at the crown and hairline. It is not approved for use in women or children.

  • Treats male pattern hair loss (androgenetic alopecia)

  • Approved for men only, ages 18 and older

  • Taken as one 1 mg tablet daily

  • Blocks DHT production at the follicle

  • Distinct from Proscar (finasteride 5 mg) for BPH

Spironolactone

Spironolactone is FDA-approved for heart failure, high blood pressure, fluid retention, and conditions caused by excess aldosterone. It is not approved for hair loss, but dermatologists commonly prescribe it off-label to treat female pattern hair loss by blocking androgen receptors. It is generally avoided in men because of feminizing side effects.

  • Off-label treatment for female pattern hair loss

  • FDA-approved for heart failure and hypertension

  • Typically dosed 50 to 200 mg daily for hair loss

  • Blocks androgen receptors at the follicle

  • Rarely used in men due to feminizing effects

Propecia vs. Spironolactone Pros and Cons

Propecia

Propecia has a simple, fixed once-daily dose backed by nearly three decades of FDA-approved use in men. It carries known risks around sexual function and mood that patients should discuss with a doctor before starting.

Pros

  • Only FDA-approved oral pill made specifically for male hair loss

  • Simple fixed 1 mg dose, no titration or monitoring needed

  • Nearly 30 years of FDA-approved safety data since 1997

  • No blood tests required during treatment

Cons

  • Not approved for women or safe for them to handle broken tablets

  • Sexual side effects can rarely persist after stopping (post-finasteride syndrome)

  • FDA warning added for depression and suicidal thoughts

  • Higher list price than generic spironolactone, roughly $100 to $250 a month

Spironolactone

Spironolactone offers dermatologists a flexible, low-cost antiandrogen for female pattern hair loss, though it lacks FDA approval for that use. Regular blood work is needed to watch for elevated potassium, and it is not a fit for men.

Pros

  • Generic version costs roughly $10 to $40 a month without insurance

  • Dose can be adjusted to balance effectiveness and side effects

  • Also helps related concerns like acne and excess facial hair

  • Decades of cardiovascular safety data since 1960

Cons

  • Not FDA-approved for any type of hair loss

  • Requires periodic blood tests to monitor potassium levels

  • Not appropriate for men due to breast enlargement and low libido

  • Titration to an effective dose can take weeks to months

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