Finasteride vs Spironolactone for Hair Loss: Labels and Evidence

Both drugs work against male hormones, which is why they get compared. This page sets out what each label says, what the hair studies found, and what each costs online. We do not give doses. Which one suits you is a call for a clinician who knows your history.

Finasteride vs spironolactone at a glance

What each drug is approved for

Finasteride's hair label is short and specific. It is approved "for the treatment of male pattern hair loss (androgenetic alopecia) in MEN ONLY" (DailyMed: Propecia label). A stronger tablet of the same drug, Proscar, treats an enlarged prostate.

Spironolactone, sold as Aldactone, was first approved in the US in 1960. MedlinePlus lists its uses as hyperaldosteronism, low potassium, heart failure and fluid buildup, and says "It is also used alone or with other medications to treat high blood pressure" (MedlinePlus: spironolactone, read 14 Nov 2026). Hair loss is not on its label. When a clinician prescribes it for hair, that is off-label, which means it is a use the FDA has not approved.

How each one works on hair

Male pattern hair loss is driven by DHT, a strong form of testosterone. Finasteride stops the body from making most of it. The label calls it a drug "that prevents conversion of testosterone to" DHT (DailyMed: Propecia label). Less DHT reaches the scalp, so follicles shrink more slowly.

Spironolactone works further down the line. It leaves hormone levels alone but blocks the receptors that hormones attach to. Its label says "Spironolactone binds to the androgen receptor" (DailyMed: Aldactone label). Androgen is the general word for male hormones such as testosterone and DHT. Blocking them helps some women with hair loss. In a man, blocking male hormones across the whole body is exactly what causes the side effects below.

What the hair studies show

Finasteride has large trials behind it. In the label's year-long studies, a panel judged photos without knowing who took what. "At 12 months, 48% of men treated with PROPECIA had an increase as compared with 7% of men treated with placebo" (DailyMed: Propecia label). A placebo is a dummy pill given for comparison.

Spironolactone's hair evidence is thinner and mostly female. A 2023 review of oral and topical spironolactone found 7 studies that "comprised 618 AGA patients (65 men, 553 women)". It concluded the drug worked, but added that "more high-quality clinical randomized controlled studies should be performed" (Wang et al., Clin Cosmet Investig Dermatol 2023, PubMed). Randomized means people are put into groups by chance, which makes a fair test. AGA is short for the same pattern hair loss.

The same review said topical use "has significantly fewer side effects and is suitable for any gender". No topical spironolactone is FDA-approved for hair. Any cream or solution sold for it is mixed by a compounding pharmacy.

Why men rarely get oral spironolactone

The main reason is breast growth. Aldactone's label says "The most common adverse reaction with ALDACTONE treatment is gynecomastia" (DailyMed: Aldactone label). Gynecomastia means swollen breast tissue in a man. In a heart failure trial, "about 9% of the male subjects developed gynecomastia", and the label adds that "Gynecomastia is usually reversible".

MedlinePlus lists other effects that matter to men, including "enlarged or painful breasts in men or women" and "difficulty maintaining or achieving an erection" (MedlinePlus: spironolactone).

Potassium is the other issue. Spironolactone makes the body hold on to potassium, and too much potassium can upset the heart rhythm. The label says to "Monitor serum potassium within one week of initiation and regularly thereafter" (DailyMed: Aldactone label). In plain words: blood tests soon after starting, and then from time to time. MedlinePlus also says to avoid salt substitutes that contain potassium.

Finasteride's side effects are different. In its hair trials, decreased libido hit 1.8% of men against 1.3% on a dummy pill, and erectile dysfunction 1.3% against 0.7% (DailyMed: Propecia label). Our finasteride side effects guide covers the full table and the reports made after approval.

Pregnancy: both carry a warning

Both drugs can affect a male baby in the womb. Women who are or may be pregnant should not handle crushed or broken finasteride tablets. The Aldactone label says to "avoid spironolactone in pregnant women or advise a pregnant woman of the potential risk to a male fetus" (DailyMed: Aldactone label). This matters most for women, who are the main users of spironolactone for hair.

Can men take finasteride and spironolactone together?

We found no trial testing the two together in men, and neither label covers the pair. For men, clinicians more often pair finasteride with minoxidil, which has more evidence. Our finasteride and minoxidil guide covers that route, and finasteride vs minoxidil compares the two on their own.

What each costs online

Most online men's hair loss programs sell finasteride, and few sell spironolactone. Plain generic finasteride starts at $0.83 a tablet at Strut Health, visit included, as checked November 14, 2026. Every finasteride plan is on our finasteride price page.

One program we track, HealthRX, lists a capsule that mixes oral minoxidil and spironolactone at $35 a month on a 3-month plan. That capsule is compounded and not FDA-approved. For the full ranked list of programs, see Best men's health programs.