What Is Finasteride Used For? Hair Loss, Prostate and More

This page explains each use, the drug class finasteride belongs to, what the trials found, and what it is not used for. We do not give doses. A clinician decides whether it suits you, and at what strength.

Finasteride uses: the two approved jobs

All three labels were read on 14 Nov 2026. The hair and prostate tablets hold the same drug at different strengths, so one is not a swap for the other. The prescriber picks the product.

Hair loss

Propecia is approved "for the treatment of male pattern hair loss (androgenetic alopecia) in MEN ONLY" (DailyMed: Propecia label). This is the use that almost every online men's health program sells. It slows the slow thinning on the crown and at the hairline that runs in families.

Enlarged prostate

The prostate grows with age in many men. When it presses on the tube that carries urine, peeing gets slow, weak or frequent. Doctors call this benign prostatic hyperplasia, or BPH; benign means it is not cancer.

The Proscar label lists three aims: "Improve symptoms", "Reduce the risk of acute urinary retention" and "Reduce the risk of the need for surgery" (DailyMed: Proscar label). Acute urinary retention means suddenly being unable to pee at all. The label also covers finasteride taken with doxazosin, another prostate drug, to slow the condition from getting worse.

Finasteride class: what kind of drug it is

MedlinePlus puts it plainly: "Finasteride is in a class of medications called 5-alpha reductase inhibitors" (MedlinePlus: finasteride). That long name describes what it blocks. 5-alpha reductase is an enzyme, a body chemical that turns testosterone into a stronger hormone called DHT.

DHT does two things that matter here. In the scalp, it shrinks hair follicles in men prone to pattern hair loss. In the prostate, it drives growth. MedlinePlus says finasteride "treats BPH by blocking the body's production of a male hormone that causes the prostate to enlarge". That one action explains both uses.

The only other drug in this class sold in the US is dutasteride (Avodart), which is approved for the prostate but not for hair loss. Our finasteride vs dutasteride guide compares the two.

Finasteride benefits: what the trials found

For hair

The hair trials followed men aged 18 to 41 for a year or more. A panel rated standard photos without knowing who took the drug. "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 used for comparison.

Hair counts told the same story. The original paper reported gains of "107 and 138 hairs vs placebo at 1 and 2 years, respectively" in a one-inch circle (Kaufman et al., JAAD 1998, PubMed). Results are slow: the label says "daily use for three months or more is necessary before benefit is observed". Our finasteride timeline goes month by month.

For the prostate

In a four-year Proscar study of about 3,000 men, the need for surgery fell from "10.1% for placebo vs 4.6% for PROSCAR". Sudden inability to pee fell from "6.6% for placebo vs 2.8% for PROSCAR" (DailyMed: Proscar label). In plain numbers, about half as many men on the drug needed surgery.

Other uses, and what finasteride is not for

MedlinePlus adds a general line: "This medication may be prescribed for other uses; ask your doctor or pharmacist for more information." Those are off-label uses, meaning uses the FDA has not approved. We do not list them, because no label backs them.

Some things finasteride is clearly not for:

• Preventing prostate cancer. The Proscar label says "PROSCAR is not approved for the prevention of prostate cancer". It also says the drug may raise the risk of high-grade prostate cancer.
• Women. Propecia "is not indicated for use in women", and pregnant women should not handle crushed or broken tablets because of the risk to a male baby.
• Children. Neither label covers children.

Finasteride also lowers PSA, the blood test used to screen for prostate cancer. The label says "PROPECIA causes a decrease in serum PSA levels" (DailyMed: Propecia label). Tell whoever orders your PSA test that you take it. Our finasteride and PSA guide explains how the result is read.

Side effects in brief

In the hair trials, decreased libido affected 1.8% of men on finasteride against 1.3% on a dummy pill, and erectile dysfunction 1.3% against 0.7%. The label also lists reports, made after approval, of sexual problems that lasted after stopping and of depression. Our finasteride side effects guide has the full picture.

What finasteride costs

Online programs sell finasteride for hair loss, not for the prostate; prostate care usually goes through your own doctor. For hair, generic finasteride starts at $0.83 a tablet at Strut Health, and the cheapest hair loss plan overall is Keeps at $14 a month, as checked November 14, 2026. Every plan is on our finasteride price page.