Dutasteride (Avodart): Uses, Dosage, Side Effects and Cost in Canada

Dutasteride is a prescription capsule for men with an enlarged prostate (BPH). Learn how it is taken, its side effects, its effect on PSA tests and why women must not handle it.

otherDoctor-reviewedPrescriptionAvailable in Canada
Illustration of a pill bottle and capsules for Dutasteride (Avodart)

Disclaimer: This article is for informational purposes only and does not constitute medical advice. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a physician or other qualified health provider with any questions you may have regarding a medical condition.

Overview

Dutasteride is a prescription medicine for men with an enlarged prostate, a condition called benign prostatic hyperplasia (BPH). In Canada, Avodart is the original brand, and generic dutasteride 0.5 mg capsules are also sold.

It belongs to the 5-alpha reductase inhibitor group, the same family as finasteride. Dutasteride shrinks the prostate and can ease problems such as a weak urine stream and needing to urinate often. It does not cure BPH, it works only while it is taken, and it is not approved for preventing prostate cancer. Some doctors prescribe it for hair loss, but that use is not authorized in Canada.

Urinary symptoms can have several causes, including prostate cancer, so they should be checked first. BC residents can speak with a BC-licensed doctor by phone through Avee Health about their symptoms and next steps. A prescription is not guaranteed.

In Canada, dutasteride (Avodart) is authorized for men with an enlarged prostate:

  • On its own, to treat symptoms of benign prostatic hyperplasia (BPH) in men with an enlarged prostate, and to lower the risk of sudden urinary blockage (acute urinary retention) and of BPH surgery
  • Together with the alpha blocker tamsulosin, for moderate to severe BPH symptoms in men with an enlarged prostate

It is not authorized for preventing prostate cancer, for hair loss, or for use in women or children. It has not been studied for BPH without symptoms.

Generic name

Dutasteride

Drug class

5-alpha reductase inhibitor (type I and II)

Category

other

Availability

Prescription required

In Canada

Available

How Dutasteride Works

The prostate grows under the influence of a hormone called dihydrotestosterone (DHT), which the body makes from testosterone using enzymes called 5-alpha reductases. Dutasteride blocks both the type I and type II forms of this enzyme, so less DHT is made.

In clinical studies, blood DHT levels fell by about 85% after 1 week and about 90% after 2 weeks. With less DHT, the enlarged prostate shrinks over time, which can improve urine flow and reduce the risk of sudden urinary blockage and of BPH surgery.

Dutasteride stays in the body for a long time. Its half-life is 3 to 5 weeks, and DHT levels take about 4 months to return to normal after stopping.

Dosage Instructions of Dutasteride

Take dutasteride exactly as your prescriber directs. The Canadian Avodart product monograph gives this usual adult dose for men:

  • One 0.5 mg capsule once a day, with or without food
  • When used with the alpha blocker tamsulosin: one dutasteride 0.5 mg capsule and one tamsulosin 0.4 mg capsule, each once a day
  • Swallow the capsule whole. Do not chew or open it, because the contents can irritate the mouth and throat.
  • No dose change is needed for older men or for kidney problems. Caution is advised in liver disease.

Symptoms may improve after about 3 months in some men, but it can take up to 6 months to know whether treatment is working.

Missed dose: take the next capsule at the usual time. Do not take extra capsules to make up for it.

Storage Instructions

Store at room temperature, between 15°C and 30°C. Keep out of the reach and sight of children. Return any cracked or leaking capsules to your pharmacist.

Side Effects of Dutasteride

In the first 6 months of the main trials, the most common side effects judged related to the medicine were, compared with placebo:

  • Erection problems (impotence): 4.7%, compared with 1.7%
  • Lower sex drive: 3.0%, compared with 1.4%
  • Ejaculation problems: 1.4%, compared with 0.5%
  • Breast swelling or tenderness: 0.5%, compared with 0.2% in the first 6 months. Rates rose to about 1% in later months.

These sexual side effects mostly appear early and become less common, but in a small number of men they continued after stopping. Dizziness is also more common when dutasteride is taken with tamsulosin. Body hair loss and unusual hair growth are rare.

Get medical help promptly if you have:

  • Swelling of the eyelids, face or lips, wheezing or chest tightness, or hives, which can be an allergic reaction
  • Breast lumps or nipple discharge
  • Shortness of breath, swelling in the legs or fast weight gain, which can be signs of heart failure
  • Low mood, or pain or swelling in the testicles

Important Safety Information About Dutasteride

  • Men only: dutasteride is contraindicated in women and children. Women who are pregnant or may be pregnant must not handle the capsules, as the medicine is absorbed through the skin and may affect the development of a male baby.
  • Allergy: do not take it if you are allergic to dutasteride, other 5-alpha reductase inhibitors or any ingredient.
  • Prostate cancer: urinary symptoms and prostate cancer can occur together, so an assessment is needed before treatment, with regular exams and PSA tests afterwards. In a 4-year trial of men with a recent negative biopsy, more high-grade (Gleason 8-10) prostate cancers were found with dutasteride (0.9%) than with placebo (0.6%). No causal link has been established.
  • PSA tests: dutasteride lowers PSA about 50% within 3 to 6 months. A rise in PSA while on treatment should be checked, even if it is in the normal range.
  • Heart failure: heart failure was reported more often in men taking dutasteride with tamsulosin (0.9%) than with dutasteride alone (0.2%) over 4 years. A causal link has not been established. Tell your doctor about heart problems.
  • Breast changes: breast enlargement, tenderness and breast cancer have been reported. Report lumps or nipple discharge promptly.
  • Blood donation: do not donate blood while taking dutasteride or for at least 6 months after the last dose.
  • Fertility: sperm count, semen volume and sperm movement fell in a study of healthy men, and some men had a large drop in sperm count. The effect on any one man's fertility is not known.
  • Liver and urinary flow: use caution with liver disease. Men with a large leftover urine volume or a very weak stream may not be suitable and need monitoring.

Drug Interactions

Tell your prescriber and pharmacist about everything you take, including vitamins and natural products. Points to know:

  • Strong, long-term CYP3A4 inhibitors such as ritonavir, ketoconazole, verapamil, diltiazem, cimetidine and ciprofloxacin may raise dutasteride levels, so they are combined with caution
  • Grapefruit juice, and herbal products such as milk thistle or St. John's wort, may affect dutasteride levels. The monograph advises care
  • Tamsulosin and other alpha blockers can be taken with dutasteride. The two do not change each other's levels
  • Warfarin and digoxin: dutasteride did not change their effect in studies
  • PSA tests: dutasteride lowers PSA by about 50% within 3 to 6 months. Always tell the doctor who orders a PSA test that you take it
  • Food does not change how dutasteride is absorbed

Brands & DIN Number of Dutasteride

Brand Names

Avodart

Key Takeaways

  • 1Dutasteride (Avodart) is a prescription capsule authorized in Canada for men with an enlarged prostate (BPH). It is not authorized for hair loss or for preventing prostate cancer.
  • 2The usual dose is one 0.5 mg capsule once a day, swallowed whole. It can take 3 to 6 months to see the full benefit.
  • 3It is for men only. Women and children must not take it, and women who are or may be pregnant must not handle the capsules.
  • 4Common side effects are erection problems, lower sex drive, ejaculation problems and breast swelling or tenderness. Some of these can continue after stopping.
  • 5It lowers PSA by about half, so tell any doctor ordering a PSA test. Regular checkups, including a PSA test and prostate exam, are advised.
  • 6Do not donate blood while taking it or for at least 6 months after the last dose.
  • 7Report breast lumps or nipple discharge, signs of heart failure, or an allergic reaction to a doctor promptly.

Frequently Asked Questions

Do I need a prescription for dutasteride in Canada, and how do I get it in BC?
Yes. Dutasteride is a prescription medicine in Canada. BC residents can speak with a BC-licensed doctor by phone through Avee Health about their symptoms. Before treatment, the Canadian monograph calls for an assessment to rule out other urological conditions, including prostate cancer, so the doctor may ask for tests such as a PSA blood test or an in-person examination. A prescription is not guaranteed.
How long does dutasteride take to work?
Some men notice better urinary symptoms after about 3 months, but it can take up to 6 months to know whether the treatment is working. Keep taking it as prescribed and stay in touch with your doctor.
Can dutasteride be used for hair loss?
Not as an authorized use. In Canada, Avodart is authorized for an enlarged prostate (BPH) in men, not for hair loss. Some doctors prescribe dutasteride for hair loss off-label, but the product monograph gives no guidance for that use. Finasteride 1 mg is the medicine authorized in Canada for male pattern hair loss.
Does dutasteride cause sexual side effects?
It can. The most common side effects are erection problems, lower sex drive, ejaculation problems and breast swelling or tenderness. In a small number of men these sexual effects have continued after stopping the medicine. Talk to your doctor if they bother you.
What is the difference between dutasteride and finasteride?
Both are 5-alpha reductase inhibitors. Dutasteride blocks both the type I and type II enzymes. Finasteride mainly blocks type II, and it comes in a 5 mg strength for an enlarged prostate and a 1 mg strength for hair loss. A doctor can explain which fits your situation.
Can a pregnant partner touch dutasteride capsules?
Dutasteride is absorbed through the skin. Women who are pregnant or may be pregnant should not handle the capsules, because the medicine may affect the development of a male baby. If anyone touches a leaking capsule, the area should be washed right away with soap and water.
Does dutasteride affect PSA tests or blood donation?
Dutasteride lowers PSA levels by about half within 3 to 6 months, so tell any doctor ordering a PSA test that you take it. Do not donate blood while taking it or for at least 6 months after your last dose.
How much does dutasteride cost in Canada?
The price depends on the brand, the number of capsules and the pharmacy, and generic versions are available. Coverage varies by plan, so check with your pharmacy or insurer.
Written By
Avee Editorial

Avee Editorial

Avee Editorial Team