HealthyStudy

Finasteride vs dutasteride

Propecia: approved for hair lossAvodart: approved for another condition

Finasteride and dutasteride belong to the same class and are frequently discussed together for hair loss. In the United States only one of them is approved for it. This page sets out what each label actually covers.

Side by side, straight from the labels

This table is generated from the two source labels, not typed out by hand, so it cannot drift from what the regulator approved.

From the FDA labels

Label sectionPropeciaFINASTERIDEAvodartDUTASTERIDE
Active ingredientFinasterideType II 5-alpha reductase inhibitorDutasterideType I and type II 5-alpha reductase inhibitor
SupplyPrescriptionPrescription
Boxed warningNoneNone
What the FDA approved it for
  • PROPECIA ® is indicated for the treatment of male pattern hair loss (androgenetic alopecia) in MEN ONLY.
  • Efficacy in bitemporal recession has not been established.
  • PROPECIA is not indicated for use in women.
  • PROPECIA is a 5α-reductase inhibitor indicated for the treatment of male pattern hair loss (androgenetic alopecia) in MEN ONLY.
  • AVODART is a 5 alpha-reductase inhibitor indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate to:
  • reduce the risk of the need for BPH-related surgery. AVODART in combination with the alpha-adrenergic antagonist, tamsulosin, is indicated for the treatment of symptomatic BPH in men with an enlarged prostate. Limitations of Use: AVODART is not approved for the prevention of prostate cancer.
Forms and strengths
  • PROPECIA tablets (1 mg) are tan, octagonal, film-coated convex tablets with "stylized P" logo on one side and PROPECIA on the other. 1 mg tablets.
  • 0.5-mg, opaque, dull yellow, gelatin capsules imprinted with "GX CE2" in red ink on one side. 0.5-mg soft gelatin capsules
How the label says it is taken
  • PROPECIA may be administered with or without meals.
  • The recommended dose of PROPECIA is one tablet (1 mg) taken once daily.
  • In general, daily use for three months or more is necessary before benefit is observed.
  • Continued use is recommended to sustain benefit, which should be re-evaluated periodically.
  • Monotherapy: 0.5 mg once daily.
  • Combination with tamsulosin: 0.5 mg once daily and tamsulosin 0.4 mg once daily.
  • Dosing considerations: Swallow whole. May take with or without food. Monotherapy The recommended dose of AVODART is 1 capsule (0.5 mg) taken once daily. Combination with Alpha-adrenergic Antagonist The recommended dose of AVODART is 1 capsule (0.5 mg) taken once daily and tamsulosin 0.4 mg taken once daily.
Most common adverse reactions
  • most common adverse reactions, reported in ≥1% of patients treated with PROPECIA and greater than in patients treated with placebo are: decreased libido, erectile dysfunction and ejaculation disorder.
  • the most frequently reported adverse reactions. Table 2 presents the only clinical adverse reactions considered possibly, probably or definitely drug related by the investigator, for which the incidence on PROSCAR was ≥1% and greater than placebo over the 4 years of the study.
  • most common adverse reactions, reported in ≥1% of subjects treated with AVODART and more commonly than in subjects treated with placebo, are impotence, decreased libido, ejaculation disorders, and breast disorders. To report SUSPECTED ADVERSE REACTIONS, contact Waylis Therapeutics LLC at 888-514-4727 or FDA at 1-800-FDA-1088 or www.
  • most common adverse reactions reported in subjects receiving AVODART were impotence, decreased libido, breast disorders (including breast enlargement and tenderness), and ejaculation disorders. The most common adverse reactions reported in subjects receiving combination therapy (AVODART plus tamsulosin) were impotence, decreased libido, breast disorders (including breast enlargement and...
  • most common adverse reaction leading to trial withdrawal was impotence (1%). • In the clinical trial evaluating the combination therapy, trial withdrawal due to adverse reactions occurred in 6% of subjects receiving combination therapy (AVODART plus tamsulosin) and 4% of subjects receiving AVODART or tamsulosin as monotherapy.
Warnings and precautions
  • PROPECIA is not indicated for use in women or pediatric patients.
  • Women should not handle crushed or broken PROPECIA tablets when they are pregnant or may potentially be pregnant due to potential risk to a male fetus.
  • PROPECIA causes a decrease in serum PSA levels.
  • Any confirmed increase in PSA while on PROPECIA may signal the presence of prostate cancer and should be evaluated, even if those values are still within the normal range for men not taking a 5α-reductase inhibitor. 5α-reductase inhibitors may increase the risk of high-grade prostate cancer.
  • AVODART reduces serum prostate-specific antigen (PSA) concentration by approximately 50%. However, any confirmed increase in PSA while on AVODART may signal the presence of prostate cancer and should be evaluated, even if those values are still within the normal range for untreated men.
  • AVODART may increase the risk of high-grade prostate cancer.
  • Prior to initiating treatment with AVODART, consideration should be given to other urological conditions that may cause similar symptoms.
  • Women who are pregnant or may be pregnant should not handle AVODART capsules due to potential risk to a male fetus.
  • Patients should not donate blood until 6 months after their last dose of AVODART. Effects on Prostate-Specific Antigen (PSA) and the Use of PSA in Prostate Cancer Detection In clinical trials, AVODART reduced serum PSA concentration by approximately 50% within 3 to 6 months of treatment.
Contraindications
  • PROPECIA is contraindicated in the following: Pregnancy.
  • Finasteride use is contraindicated in women when they are or may potentially be pregnant.
  • Because of the ability of Type II 5α-reductase inhibitors to inhibit the conversion of testosterone to 5α-dihydrotestosterone (DHT), finasteride may cause abnormalities of the external genitalia of a male fetus of a pregnant woman who receives finasteride.
  • If this drug is used during pregnancy, or if pregnancy occurs while taking this drug, the pregnant woman should be apprised of the potential hazard to the male fetus. In female rats, low doses of finasteride administered during pregnancy have produced abnormalities of the external genitalia in male offspring.
  • Pregnancy. Dutasteride use is contraindicated in women who are pregnant.
  • Patients with previously demonstrated, clinically significant hypersensitivity (e.g., serious skin reactions, angioedema) to AVODART or other 5 alpha-reductase inhibitors.
Drug interactions
  • Cytochrome P450-Linked Drug Metabolizing Enzyme System No drug interactions of clinical importance have been identified.
  • Finasteride does not appear to affect the cytochrome P450-linked drug-metabolizing enzyme system.
  • Compounds that have been tested in man include antipyrine, digoxin, propranolol, theophylline, and warfarin and no clinically meaningful interactions were found. Other Concomitant Therapy Although specific interaction studies were not performed, finasteride doses of 1 mg or more were concomitantly used in clinical studies with acetaminophen, acetylsalicylic acid, α-blockers, analgesics,...
  • Use with caution in patients taking potent, chronic cytochrome P450 (CYP)3A4 enzyme inhibitors (e.g., ritonavir).
Label version14 October 202412 March 2025

Only finasteride is approved for hair loss in the United States

Written by us

The Propecia label covers male pattern hair loss. The US label for dutasteride covers benign prostatic hyperplasia and says nothing about hair. Dutasteride has been approved for androgenetic alopecia by regulators in some other countries, which is why the two are so often mentioned together, but that approval does not exist in the United States and does not appear in the label linked from this page.

They inhibit different forms of the same enzyme

Written by us

Finasteride inhibits type II 5-alpha reductase. Dutasteride inhibits both type I and type II. Both enzymes convert testosterone into dihydrotestosterone, and the dutasteride label reports a greater reduction in circulating dihydrotestosterone as a result.

That is a pharmacological difference stated in the labels. It is not, on its own, a statement about outcomes in hair loss, and neither US label makes one.

Both are contraindicated in pregnancy

Written by us

Both labels contraindicate use in women who are or may become pregnant and both warn about handling the product, because of the risk to a male fetus from inhibition of dihydrotestosterone. This is the one safety point where the two documents say substantially the same thing.

Common questions

Is dutasteride approved for hair loss?
Not in the United States. Its US label covers benign prostatic hyperplasia. Some other regulators have approved it for androgenetic alopecia.
Is dutasteride stronger than finasteride?
Its label reports a greater reduction in circulating dihydrotestosterone, because it inhibits both forms of the enzyme rather than one. That is a measurement reported in the label, not a comparison of results in hair loss, and the labels do not compare the two.

Sources

Every fact above comes from one of these documents. The date is the effective date of the label version this page was built from.

Page last updated: 29 July 2026

Compiled by the HealthyStudy editorial team from FDA source documents. No medical reviewer is credited on this page, because none reviewed it.