Finasteride
Pronunciation: fi-NAS-tur-ide.
- Generic name
- finasteride
- Brand names
- Propecia, Finasteride Accord, Proscar, Finax, Finpecia, Finast
- Drug class
- 5-alpha reductase inhibitor
Availability and supply rules vary by country
Trade names by country: United States · Canada
Australia: · Full directory
What finasteride is and how it works
Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.
Mechanism of action: how finasteride works
Finasteride is a competitive and specific inhibitor of type II 5-alpha reductase, the enzyme responsible for converting testosterone to dihydrotestosterone (DHT). By reducing DHT levels, finasteride decreases prostate volume and slows the progression of androgen-dependent hair loss. (1)
What finasteride is used for
Benign prostatic hyperplasia (BPH)
Used at 5 mg once daily to shrink an enlarged prostate and improve urinary symptoms. (2)
Male pattern hair loss (androgenetic alopecia)
Used at 1 mg once daily in men only to slow hair loss and promote regrowth. (2)
Before taking finasteride
Do not take / not appropriate for
- Contraindicated in women (especially during pregnancy), children, and those with hypersensitivity to finasteride. (Contraindication) (2)
- Finasteride may mask elevated PSA levels, potentially delaying prostate cancer diagnosis. (Contraindication) (2)
Tell your clinician about
(2)How to take finasteride
- General Instructions: Take finasteride exactly as prescribed, usually once daily, with or without food. Do not crush or break the tablets.. Adult Dosing: For BPH: 5 mg orally once daily. For male pattern hair loss: 1 mg orally once daily.. Pediatric Dosing: Finasteride is not approved for use in children or adolescents.. Administration: Swallow the tablet whole with a glass of water. Take at the same time each day for best results.. When To Stop: Do not stop taking finasteride without consulting your healthcare provider. Stopping may reverse its benefits over time.. Storage: Store at room temperature (20–25°C/68–77°F), away from moisture and heat. Keep out of reach of children.
- This page does not provide a dose calculator. Dosing must follow the prescriber, pharmacist, or product label.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (2)
Missed dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue your regular schedule; do not take an extra dose to make up for it.
Overdose
If you or someone else has taken too much finasteride, seek emergency medical attention or contact a poison control center immediately. There is no specific antidote; treatment is supportive. (2)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms to a healthcare professional.
Decreased libido
Incidence: Reported in about 1.8% of patients vs 1.3% with placebo
Erectile dysfunction
Incidence: Reported in about 1.3% of patients vs 0.7% with placebo
Ejaculation disorder / decreased semen volume
Incidence: Reported in about 1.2% of patients vs 0.7% with placebo
Serious warnings
Finasteride is for use by men only — serious
Symptoms: Finasteride is for use by men only. Women who are or may become pregnant should not handle crushed or broken tablets. May increase risk of high-grade prostate cancer; discuss risks with your doctor. Can cause sexual side effects, including decreased libido and erectile dysfunction. May affect PSA test results for prostate cancer screening.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Contraindications recorded in the clinician database — serious
Symptoms: Contraindications recorded in the clinician database: Contraindicated in women (especially during pregnancy), children, and those with hypersensitivity to finasteride. Use with caution in patients with liver impairment. Finasteride may mask elevated PSA levels, potentially delaying prostate cancer diagnosis.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Mood and psychiatric effects — serious
Symptoms: Mood and psychiatric effects: post-marketing reports and regulatory reviews (including a 2025-2026 European Medicines Agency safety review) have linked finasteride to depression, mood changes, and suicidal thoughts or behavior. Tell your healthcare provider promptly if you notice new or worsening depression, anxiety, or thoughts of self-harm while taking this medicine.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Male breast cancer has been reported in men taking finasteride after it reached the market, although a causal link has not been firmly established — serious
Symptoms: Male breast cancer has been reported in men taking finasteride after it reached the market, although a causal link has not been firmly established. Tell your healthcare provider promptly about any breast lumps, pain, or nipple discharge.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Recorded interactions | Finasteride has a low potential for drug interactions. However, always inform your healthcare provider about all medications, supplements, and herbal products you are taking. No significant interactions have been identified, but caution is advised when used with other medications affecting hormone levels. | (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Finasteride is not used by women and is contraindicated in pregnancy (Pregnancy Category X) because of the risk of abnormalities in a male fetus's genital development. Women who are or may become pregnant should not handle crushed or broken tablets; handling intact, coated tablets normally is not a known risk. (2)
Breastfeeding
The FDA label states Propecia (finasteride) is not indicated for use in women, and it is not known whether finasteride is excreted in human milk. Because there is no approved use in women, this does not affect typical dosing, but anyone breastfeeding who has been exposed to finasteride should discuss it with the clinician managing their care. (2)
Children
Frequency: Not applicable. Weight Based: Not recommended for pediatric use. Max Daily Dose: Not applicable. Max Single Dose: Not applicable. Age Restrictions: Safety not established in children (2)
Renal_impairment
The FDA label states no dose adjustment is needed for kidney impairment: in people with chronic kidney impairment, finasteride blood levels and elimination half-life after a single dose were similar to those with normal kidney function, although levels of its inactive breakdown products (metabolites) were higher because less was cleared through urine and more through stool. The effect of liver impairment on finasteride has not been formally studied; because the liver breaks down finasteride extensively, the label advises caution in people with abnormal liver function, and the treating clinician should be told about any liver disease before starting the medicine. (2)
Hepatic_impairment
The FDA label states no dose adjustment is needed for kidney impairment: in people with chronic kidney impairment, finasteride blood levels and elimination half-life after a single dose were similar to those with normal kidney function, although levels of its inactive breakdown products (metabolites) were higher because less was cleared through urine and more through stool. The effect of liver impairment on finasteride has not been formally studied; because the liver breaks down finasteride extensively, the label advises caution in people with abnormal liver function, and the treating clinician should be told about any liver disease before starting the medicine. (2)
Monitoring
(2)Storage
Store at room temperature, 15-30°C (59-86°F). Keep the container closed and protect from moisture. Keep out of reach of children.
Professional information
Clinician-facing context only. This section does not replace current product labeling.
General
Indication: Benign prostatic hyperplasia (BPH)
Dose summary: The standard adult dose for the treatment of benign prostatic hyperplasia (BPH) is 5 mg orally once daily. For male pattern hair loss, the dose is 1 mg orally once daily.
Renal context: The FDA label states no dosage adjustment is necessary in patients with renal impairment: in patients with chronic renal impairment (creatinine clearance 9.0-55 mL/min), AUC, peak plasma concentration, half-life, and protein binding of finasteride after a single dose were similar to healthy volunteers, though plasma concentrations of finasteride's metabolites were higher (about a 60% increase in total metabolite AUC) due to decreased urinary excretion, offset by increased fecal excretion. The effect of hepatic impairment on finasteride pharmacokinetics has not been studied; because finasteride is extensively metabolized in the liver, the label advises caution in patients with liver function abnormalities. (1) (2)
Frequently asked questions
How long does it take for finasteride to work?
For BPH, symptom improvement may be seen within a few months, but full benefits can take up to 6 months. For hair loss, noticeable effects may take 3–6 months, with maximum benefit after 12 months of continuous use.
Can women use finasteride?
No, finasteride is not approved for use in women and can cause birth defects if used during pregnancy. Women who are or may become pregnant should not handle crushed or broken tablets.
Are the sexual side effects permanent?
Most sexual side effects, such as decreased libido or erectile dysfunction, resolve after stopping the medication. However, in rare cases, some symptoms may persist.
Does finasteride prevent prostate cancer?
Finasteride may lower the overall risk of prostate cancer but may increase the risk of developing high-grade prostate cancer. Discuss the risks and benefits with your doctor.
Can I stop taking finasteride suddenly?
You should not stop taking finasteride without consulting your healthcare provider. Stopping may reverse its benefits over time.
Is it safe to donate blood while taking finasteride?
You should not donate blood while taking finasteride and for at least 1 month after stopping, to prevent exposure to pregnant women.
Does finasteride interact with other medications?
Finasteride has a low risk of drug interactions, but always inform your healthcare provider about all medications and supplements you are taking.
What happens if I take too much Finasteride?
Taking too much Finasteride may not necessarily lead to more severe side effects immediately, as the body's response is often dose-dependent but not linear. However, an overdose could potentially exacerbate common side effects like sexual dysfunction. If you suspect an overdose, seek immediate medical attention or contact emergency services.
Can I drink alcohol while taking Finasteride?
There is no direct known interaction between Finasteride and alcohol that would cause immediate harm. However, excessive alcohol consumption can worsen symptoms of benign prostatic hyperplasia (BPH) and may also contribute to liver issues, which could indirectly affect how Finasteride is metabolized. It's generally advisable to consume alcohol in moderation and discuss any concerns with your healthcare provider.
Is Finasteride safe during pregnancy?
Finasteride is contraindicated in women who are or may become pregnant due to its potential to cause abnormalities of the external genitalia of a male fetus. It is classified as Pregnancy Category X. Therefore, it is absolutely crucial for women who are pregnant or planning to conceive to avoid contact with crushed or broken Finasteride tablets and to consult their healthcare provider immediately if exposure occurs or if they have any questions.
What is the mechanism of action of finasteride?
Finasteride is a competitive and specific inhibitor of type II 5-alpha reductase, the enzyme responsible for converting testosterone to dihydrotestosterone (DHT). By reducing DHT levels, finasteride decreases prostate volume and slows the progression of androgen-dependent hair loss. (1)
What is the generic name of Finasteride?
The generic name is finasteride. It is sold under brand names including Propecia, Finasteride Accord, Proscar, Finax, Finpecia, Finast.
What class of drug is finasteride?
Finasteride is classed as: 5-alpha reductase inhibitor.
References
- Finasteride — clinician-authored medicine recordMedGuideGlobal · International · accessed 2026-08-06 · source 1
- PROPECIA (finasteride) 1 mg tablet — prescribing/consumer labelingU.S. National Library of Medicine DailyMed · United States · accessed 2026-08-06 · source 2
- JOHNSON FOAM PRO (FINASTERIDE FOAM WITH 5% MINOXIDIL) AEROSOL, FOAM [JOHNSON BIOPHARMACEUTICAL INC.] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
- Finasteride — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
- Finasteride — FDA approval record (Drugs@FDA ANDA090060)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
- finasteride — RxNorm normalized drug concept (RXCUI 25025)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6
Brand names by country
Single-ingredient finasteride names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- PROSCAR5 mg · organon llc
- PROPECIA1 mg · organon llc
Canada
- PROSCAR
- PROPECIA
- ACH-FINASTERIDE