Dutasteride
Type I and type II 5-alpha reductase inhibitor. Sold as Avodart.
Dutasteride belongs to the same class as finasteride but blocks both type I and type II 5-alpha reductase rather than type II alone. In the United States it is approved only for benign prostatic hyperplasia. It is approved for hair loss in some other countries, which is a frequent source of confusion.
Brands and what each one is approved for
One active ingredient can hold several separate FDA approvals. They are different documents with different approved uses, and mixing them up is the most common mistake made about these medications.
| Brand | Status for this use | Supply | Label version |
|---|---|---|---|
| AvodartWaylis Therapeutics LLC | Approved for another condition | Prescription | 12 March 2025 |
How it works
Written by us
The label describes inhibition of both isoforms of 5-alpha reductase, the enzymes that convert testosterone into dihydrotestosterone, and reports a greater reduction in circulating dihydrotestosterone than a type II inhibitor alone.
From the mechanism of action section of the Avodart label
Dutasteride inhibits the conversion of testosterone to DHT. DHT is the androgen primarily responsible for the initial development and subsequent enlargement of the prostate gland.
What the FDA approved it for
The approved uses, as worded in the label.
From the FDA label
- 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
The presentations and strengths listed in the label.
From the FDA label
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
What the label states about administration. It is not a dosing instruction for any individual.
From the FDA label
- 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
The adverse reactions the label reports as most common.
From the FDA label
- 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
The warnings and precautions section of the label.
From the FDA label
- 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
Situations in which the label states the medication must not be used.
From the FDA label
- 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
Interactions the label singles out.
From the FDA label
Use with caution in patients taking potent, chronic cytochrome P450 (CYP)3A4 enzyme inhibitors (e.g., ritonavir).
Pregnancy and breastfeeding
The opening of the pregnancy section of the label. The full section is longer and is in the source document.
From the FDA label
AVODART is contraindicated for use in pregnancy because it may cause harm to the male fetus. AVODART is not indicated for use in women. AVODART is a 5 alpha‑reductase inhibitor that prevents conversion of testosterone to dihydrotestosterone (DHT), a hormone necessary for normal development of male genitalia.
Generic or brand
Written by us
Generic dutasteride is approved and available.
The FDA label database lists 9 approved generic applications for this ingredient.
What affects the cost
Written by us
Dutasteride is generic and inexpensive relative to brand products, but its US approval does not cover hair loss. This site does not track prices and does not link to sellers.
Common questions
- Is dutasteride approved for hair loss in the United States?
- No. The US label covers benign prostatic hyperplasia. Some other regulators have approved dutasteride for androgenetic alopecia, but the label quoted on this page is the US one and it does not.
- How does it differ from finasteride?
- Finasteride inhibits type II 5-alpha reductase. Dutasteride inhibits both type I and type II. The comparison page sets out what each label says side by side.
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.
FDA prescribing information for Avodart
Waylis Therapeutics LLC. Label version 4, effective 12 March 2025.
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.