Medically Reviewed on 5/12/2022

Generic Name: dutasteride

Brand Name: Avodart

Drug Class: 5-alpha reductase inhibitors

What is dutasteride, and what is it used for?

Dutasteride is a medication used to treat prostate enlargement (benign prostatic hyperplasia) in adult males. Dutasteride helps shrink and slow down the growth of prostate tissue and relieves associated urinary symptoms. Dutasteride works by inhibiting 5-alpha reductase, the enzyme that catalyzes the conversion of testosterone into dihydrotestosterone.

Dihydrotestosterone is the male hormone (androgen) that is primarily responsible for the development and growth of the external male genitals and prostate gland, the male reproductive organ, while testosterone is mainly responsible for growth in puberty, male hair pattern, and increased muscle mass. The enzyme 5-alpha reductase exists in two isoforms, type-1 that is found mainly in the liver and skin, and type-2, the major form in the prostate tissue.

Dutasteride forms a stable complex with both types of 5-alpha reductase and blocks their catalytic activity, which results in lower levels of dihydrotestosterone and inhibition of prostate tissue growth.

Dutasteride is approved by the FDA in the treatment of symptomatic benign prostatic hyperplasia (BPH) to improve symptoms, reduce the risk of acute urinary retention, and the need for prostate surgery. It may also be used off-label to treat male pattern baldness.


  • Do not use dutasteride in patients with hypersensitivity to dutasteride, other 5-alpha reductase inhibitors or any of the components of dutasteride
  • Dutasteride is not intended for use in women or children
  • Exposure to dutasteride during pregnancy can cause harm to male fetus
  • Prior to initiating dutasteride therapy, rule out other urological conditions such as obstructive uropathy; patients with high amount of residual urine or severely reduced urine flow may not be good candidates for dutasteride therapy
  • Use with caution in patients with liver disease
  • Men treated with dutasteride should not donate blood for at least 6 months after receiving their last dose
  • Patients should be evaluated for prostate cancer before initiating dutasteride therapy, and periodically thereafter; dutasteride reduces prostate-specific antigen (PSA) levels by 40-50%; new PSA baseline level should be determined after 3-6 months of treatment; increase in PSA levels during dutasteride therapy, even within normal limits, may indicate the presence of prostate cancer
  • Dutasteride may increase the risk for high-grade prostate cancer


Signs of Prostate Cancer: Symptoms, PSA Test, Treatments See Slideshow

What are the side effects of dutasteride?

Common side effects of dutasteride include:

  • Impotence
  • Reduced sexual drive (libido)
  • Ejaculation disorder
  • Breast tissue enlargement (gynecomastia) and tenderness
  • Increase in the levels of hormones including:
    • Luteinizing hormone
    • Testosterone
    • Thyroid stimulating hormone
  • Testicular pain and swelling

Less common side effects of dutasteride include:

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug.

Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.

What are the dosages of dutasteride?


  • 0.5 mg


Benign Prostatic Hyperplasia (BPH)

  • 0.5 mg orally once/day

Dosing Modifications

  • Renal impairment: Dose adjustment is not necessary
  • Hepatic impairment: Dose adjustment is not necessary


  • Safety and efficacy not established


  • In volunteer studies, single doses of up to 80 times the therapeutic dose, and daily doses of 10 times the therapeutic dose have not revealed any significant adverse effects.
  • There is no specific antidote for dutasteride. Overdosage may be treated with symptomatic and supportive therapy as appropriate.

What drugs interact with dutasteride?

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information.

Check with your doctor or health care provider if you have any questions about the medication.

Pregnancy and breastfeeding

  • Dutasteride is not intended for use in women
  • Dutasteride is absorbed through the skin; pregnant women should not handle dutasteride capsules; may cause harm to male fetus
  • Breastfeeding women should avoid exposure to dutasteride; there is no information whether the drug is present in milk, or its effects on milk production or on the breastfed infant
  • If pregnant or breastfeeding women come into contact with leaking capsules, the contact area should be washed immediately with soap and water

What else should I know about dutasteride?

  • Take dutasteride exactly as prescribed
  • Handle dutasteride carefully and avoid exposing children and women to the drug; dutasteride exposure during pregnancy can harm male fetus
  • Keep dutasteride safely out of reach of children
  • Do not donate blood for at least 6 months after the last dose of dutasteride to prevent pregnant women from receiving dutasteride in blood transfusions


Dutasteride is a medication used to treat prostate enlargement (benign prostatic hyperplasia) in adult males by shrinking and slowing the growth of prostate tissue, and relieving urinary symptoms. Dutasteride is not intended for use in women or children. Common side effects of dutasteride include impotence, reduced sexual drive (libido), ejaculation disorder, breast tissue enlargement (gynecomastia) and tenderness, increase in the levels of hormones (luteinizing hormone, testosterone, thyroid stimulating hormone), and testicular pain and swelling.

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You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Medically Reviewed on 5/12/2022