Hair loss
Finasteride (Propecia)
finasteride / pronounced [fin as' ter ide]
Oral DHT blocker. Standard of care for male-pattern hair loss. ~80% slow shedding, ~60% regrow.
- Manufacturer
- Multiple (Merck originated as Propecia)
- FDA approved
- 1997
FDA-approved for
- Androgenetic alopecia (male pattern hair loss)
- Benign prostatic hyperplasia
Why is Finasteride (Propecia) prescribed?
Finasteride is an oral 5-alpha reductase inhibitor, FDA-approved for male-pattern hair loss (1mg) and BPH (5mg). The hair-loss dose is 1mg daily. Originally branded as Propecia; widely generic since 2013.
FDA-approved indications:
- Androgenetic alopecia (male pattern hair loss)
- Benign prostatic hyperplasia
How does Finasteride (Propecia) work?
Blocks the enzyme that converts testosterone into DHT (dihydrotestosterone). DHT is the androgen that miniaturizes hair follicles in genetically susceptible men. Lower DHT → less follicle miniaturization → less shedding, partial regrowth.
Who qualifies for Finasteride (Propecia)?
Adult men with male-pattern hair loss. Not for women of childbearing potential (can harm male fetus). Discuss with clinician if you have liver disease, prostate cancer history, or are planning conception.
How should Finasteride (Propecia) be used?
1mg orally once daily. Effects begin at 3-6 months; full effect at 12 months. Discontinuation reverses gains within 6-12 months.
What should I do if I forget a dose?
Finasteride is dosed daily. If missed: skip the dose if more than 12 hours late, take it next day at usual time. Do not double up. Missing occasional doses doesn't significantly affect long-term efficacy, but consistency matters for sustained DHT suppression — set a daily reminder.
What side effects can Finasteride (Propecia) cause?
Most common: small (~2-4%) rate of sexual side effects in trials (decreased libido, ED, ejaculation issues). Rare: gynecomastia, mood changes. 'Post-finasteride syndrome' is a contested phenomenon with persistent side effects after discontinuation; baseline rate appears low.
What interactions should clinicians watch for?
Finasteride has few clinically significant drug interactions. Can reduce PSA (prostate-specific antigen) levels by approximately 50%, which is important to flag to any doctor running prostate cancer screening — labs need to multiply PSA by 2 for accurate interpretation. No major interactions with statins, antihypertensives, or common cardiovascular drugs.
What special precautions should I follow?
Pregnancy & lactation
Finasteride is strictly contraindicated in pregnancy due to risk of feminization of male fetuses. Women who are or may become pregnant should avoid skin contact with crushed or broken tablets (intact tablets pose no contact risk). Topical finasteride formulations require careful application and hand-washing to prevent transfer. Generally not prescribed to anyone who could become pregnant.
Alcohol
No formal contraindication with alcohol. Some patients report mood-related side effects on finasteride (depression, anxiety in a small subset); heavy alcohol use can compound these. Moderate alcohol is generally compatible.
What does Finasteride (Propecia) cost?
Generic finasteride $10-25/month direct from pharmacy. Telehealth platforms $20-40/month bundled with consultation.
In case of emergency or overdose
There is no specific antidote for finasteride overdose. The drug has a half-life of ~5-6 hours (longer in elderly patients). Single doses up to 400 mg and multiple doses up to 80 mg/day for 3 months have been tolerated in trials without significant adverse effects. Call US Poison Control at 1-800-222-1222 if you suspect overdose; seek emergency care for severe allergic reactions, fainting, or chest pain.
Primary sources
Related clinical resources
What clinicians say
Quotes from published interviews, peer-reviewed commentary, and conference presentations. Each is attributed and linked to the original source.
“Finasteride treatment for 2 years resulted in clinically significant improvement in scalp hair growth in men with male pattern hair loss. The drug was well tolerated, and no new safety concerns were identified during extended follow-up.”
Source: Journal of the American Academy of Dermatology — Finasteride in the Treatment of Men with Androgenetic Alopecia (October 1998 — PMID 9777765)
“Women who are or may potentially be pregnant must not use Propecia, must not handle crushed or broken tablets, and should not handle the active ingredient because of the potential for absorption and the subsequent risk of abnormal development of the external genitalia of a male fetus.”
Source: FDA-approved Propecia (finasteride 1 mg) prescribing information — current label (Approved December 1997; current label 2012)