Finasteride for Hair Loss: How It Works and What the Label Says

Oral finasteride treats male pattern hair loss by blocking the enzyme that converts testosterone into DHT, the hormone that gradually shrinks hair follicles on the scalp. It is a generic version of FDA-approved Propecia, it is for men only, and it works slowly, usually taking at least three months to show any change. The label lists sexual side effects, depression and suicidal thoughts among reported risks, and women who are or may become pregnant should not handle crushed or broken tablets.

How finasteride works

In men with a genetic tendency toward hair loss, DHT binds to hair follicles on the top and front of the scalp and makes them smaller over time. Hairs grow thinner and shorter until some follicles stop producing visible hair.

Finasteride blocks type II 5-alpha reductase, the enzyme that makes DHT from testosterone. With less DHT, many follicles stop shrinking, and some recover. That is why finasteride is most useful to hold the line and to rebuild density in areas that are thinning, not to bring back areas that have been bald for years.

What to expect over time

Finasteride works only while you take it. Consistency matters more than anything else. Your provider sets the dose.

Side effects and label warnings

Most men take finasteride without problems, but you should know what the FDA label says.

Sexual side effects. In clinical trials, a small share of men reported lower libido, erection problems or ejaculation changes, including lower semen volume. The label also lists postmarketing reports of sexual dysfunction that continued after stopping treatment, as well as male infertility or reduced semen quality, testicular pain and blood in the semen.

Mood changes. Depression is listed in the label. In 2022 the FDA required that suicidal ideation and behavior be added to the Propecia labeling. MedlinePlus advises calling your prescriber right away for new or worsening depression or any thoughts of self-harm. If you are in crisis, call or text 988.

Breast changes. Breast tenderness or enlargement has been reported, along with rare reports of male breast cancer. Report any lump, pain or nipple discharge.

Allergic reactions. Rash, itching, hives, or swelling of the lips, tongue, throat or face need prompt care.

PSA tests. Finasteride lowers PSA, a blood test used in prostate cancer screening, by roughly half. Tell whoever orders your PSA test that you take it so the result is interpreted correctly. MedlinePlus also notes that finasteride may increase the risk of high-grade prostate cancer, which is worth discussing with your provider.

Pregnancy and handling rules

Finasteride is not for women and is contraindicated in women who are or may become pregnant. DHT is needed for normal development of male genitals, and finasteride can affect a male fetus.

• Women who are or may become pregnant should not handle crushed or broken tablets.
• Whole tablets are coated, which prevents contact with the active ingredient during normal handling.
• If a pregnant woman, or one who may become pregnant, touches a crushed or broken tablet, MedlinePlus advises washing the area with soap and water right away and calling her prescriber.
• Store your tablets where others cannot get to them, and do not split or crush them.

Oral tablets vs the topical finasteride alert

In April 2025, the FDA issued an alert about compounded topical finasteride products, often sprays or solutions sold online and sometimes combined with minoxidil. The key points from that alert:

• There is no FDA-approved topical finasteride product.
• From 2019 to 2024, the FDA received 32 adverse event reports with topical finasteride, similar to effects reported with oral finasteride, including sexual side effects, anxiety, depression and suicidal ideation.
• Topical products can transfer to other people through skin contact, which is a concern for women and children, and they lack the protective coating that oral tablets have.

RULE offers oral finasteride tablets only, a generic of an FDA-approved drug, prescribed after a licensed provider reviews your history.

Who should check first

Tell your provider if you have:

• Any history of depression, anxiety or other mood conditions.
• Liver disease.
• Prostate cancer or abnormal PSA results.
• Plans to conceive, since the label lists effects on semen quality.
• Any current medications or supplements.

Frequently asked questions

Does finasteride regrow hair?

It can help some men regrow hair in thinning areas, and it slows further loss for many. It tends to help most when started early, before large areas are fully bald.

What happens if I stop taking finasteride?

DHT levels return and the hair loss process resumes. MedlinePlus notes that you will probably lose hair gained during treatment within 12 months after stopping.

Are finasteride side effects permanent?

For most men who notice side effects, they resolve after stopping. The label also lists reports of sexual dysfunction that continued after stopping. Talk openly with your provider about any concerns before and during treatment.

Can my partner be affected?

The main concern is for women who are or may become pregnant handling crushed or broken tablets. Keep tablets whole and stored safely, and ask your provider about any other questions related to conception.

Talk to a licensed provider

If thinning hair is on your mind, start a secure online visit. A licensed provider will review your health history, explain the benefits and risks of finasteride and decide whether a prescription is appropriate for you.

This article is educational and is not medical advice. Rx programs require an online visit with a licensed provider. Results vary.