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Dutasteride Side Effects

Dutasteride Side Effects and Safety — What You Need to Know

Hair loss is so common among men that it’s seen as a natural part of the aging process.

But it doesn’t have to be.

Dutasteride (known by the brand name Avodart), was first developed for the treatment of prostate enlargement (benign prostatic hyperplasia, BPH). It then became an alternative to finasteride, one of the first effective oral hair loss medications to be developed.

But like finasteride, some guys are still worried about dutasteride’s side effects.

And fair enough. Even though research has consistently demonstrated that dutasteride is safe and well-tolerated by most men, like any medication it can have some side effects.

In this article, we provide a list of dutasteride side effects for both the oral dutasteride tablets as well as the topical dutasteride formula.

Dutasteride is an effective hair loss medication

Dutasteride is commonly used to treat hair loss in Asia, but it’s much less common in North America. Avodart (the brand name version of dutasteride) is prescribed more than Propecia in these countries.

Oral dutasteride capsules of 0.5 mg are an effective hair loss medication. One study found that it is even more effective than finasteride. While dutasteride 0.5 mg blocks more than 90% of DHT, finasteride 1 mg blocks only about 70% of DHT.

Read more: Dutasteride vs. finasteride for hair loss

Blocking DHT is the key to its effectiveness. Dihydrotestosterone (DHT) is a by-product of the breakdown of testosterone. It’s responsible for attacking the hair follicles and causing them to shrink. Eventually, DHT can cause the follicles to die and stop producing hair. DHT occurs more often in men, which is why they are more prone to hair loss and why this type of hair loss is called male-pattern hair loss, male-pattern baldness, or androgenetic alopecia.

By blocking DHT, dutasteride keeps hair follicles healthy and hair strands thick.

Dutasteride has been approved for hair loss treatment in many Asian countries, like Japan and South Korea. However, it has not yet been approved for this treatment in the US or Canada. This is because the patent for this drug has already expired. Getting it approved would be expensive, and the company to do the work would then face lots of competition. It’s not economically viable.

That’s why finasteride is typically used as a first-line medication for hair loss. If finasteride doesn’t work, doctors may prescribe dutasteride for hair loss for off-label use.

Note that dutasteride only works as long as the patient takes the medication. When the treatment ends, DHT levels return to normal, and hair loss may occur again. Dutasteride is also most effective when used early. That is why hair loss experts recommend starting the treatment as soon as possible.

Results from dutasteride treatment appear about 3-6 months after initiating treatment. It can take about 1 year for the full effects of the medication to occur. If you do not see improvement after 1 year, you may be one of the few 'non-responders'. If that’s you, treatment may be discontinued, as it is unlikely to begin working after 1 year. Instead, it may be better to try an alternative treatment, like finasteride.

If you’re not sure what the best treatment for your hair loss is, get help. Start your online visit with a hair loss specialist to learn about your options and find the right treatment for you.

What are dutasteride's side effects?

The side effects or adverse events of dutasteride depend to some extent on how you take it.

Oral dutasteride comes in 0.5 mg tablets that you take daily. For this dose, potential side effects include the following (we have in parentheses the estimated percentage of patients experiencing these side effects compared to finasteride 5mg):

  • Decreased libido (5% versus 6% in those who received finasteride)
  • Impotence/sexual dysfunction (7% versus 8% in those who received finasteride)
  • Ejaculatory disorder (1% versus 1% in those who received finasteride)
  • Gynaecomastia (1% versus 1% in those who received finasteride)

Less common side effects of dutasteride include:

  • Dizziness
  • Cardiac failure

There are other side effects of dutasteride reported, which include:

  • Immune system disorders: Hypersensitivity, including rash, itching, hives, localized swelling (edema), severe skin reactions, and skin swelling
  • Testicular pain and testicular swelling
  • Male breast cancer
  • Depressed mood

If you experience any side effects from taking dutasteride, consult your doctor.

Dutasteride interactions with other drugs

Drug interactions occur when the use of one drug changes the function of another. Some combinations of drugs can cause adverse reactions. So, if you can, it’s best to avoid using these drugs while using dutasteride.

Dutasteride has no known severe interactions with other drugs. There may be moderate interactions of dutasteride with Carbamazepine, Rifampicin, and St. John's wort. These drugs can reduce blood levels of dutasteride by increasing its breakdown in the liver.

On the other hand, medications like Itraconazole and erythromycin may increase levels of dutasteride in the blood.

Avoiding interactions with other drugs is one reason that you need a prescription to buy dutasteride. Always ensure you get professional medical advice when beginning this treatment. And ensure that your doctor or prescriber understands the other medications you’re taking.

Other dutasteride safety warnings

Dutasteride is not indicated for treatment in women or children. It is contraindicated in women when they are or could be pregnant because the drug could pose a risk to male fetuses.

The use of dutasteride should be used with caution in people with liver function abnormalities since the drug is broken down by the liver.

Does dutasteride cause hair loss initially?

Hair shedding is common in individuals using dutasteride. Hair shedding occurs when hair follicles come to the last phase in the hair growth cycle. Shedding the hairs allows them to begin to grow new hair strands.

This can happen because 'dormant' hair follicles, that have been affected by DHT, may become reactivated. They will shed older hairs to begin growing new ones. Hair shedding may begin 3 to 6 weeks after starting the medication and can last about 2 weeks. This is often a signal that the medication is working.

In some cases, people who take dutasteride do not see new hair growth, although the strands of hair that they currently have become healthier and thicker. They also become less likely to lose these hairs.

Does dutasteride cause high-grade prostate cancer?

The evidence suggests that it doesn’t. On the contrary, according to the National Cancer Institute, dutasteride seems to reduce the risk of getting prostate cancer.

How to buy dutasteride online

Hair loss affects millions of people. In Canada, even though it is effective at reducing hair loss, dutasteride is not commonly prescribed to treat hair loss. This is because it’s not yet approved for that purpose. Instead, the gold standard for hair loss treatment in Canada is a combination of finasteride and minoxidil.

Read more: Getting finasteride in Canada

Dutasteride is a prescription medication in Canada. To get it, you’ll need to have a visit with a qualified medical professional. They’ll evaluate your symptoms and determine whether dutasteride may be an appropriate treatment option for you.

Once you have your prescription, you can buy dutasteride online through services like Essential Clinic (we facilitate the purchase through our partner pharmacy).

Take the first step to treating your hair loss: start your online hair loss visit.


Andriole, G. L., Bostwick, D. G., Brawley, O. W., Gomella, L. G., Marberger, M., Montorsi, F., ... & Rittmaster, R. S. (2010). Effect of dutasteride on the risk of prostate cancer. N Engl J Med, 362, 1192-1202.

Nickel J. C. (2004). Comparison of clinical trials with finasteride and dutasteride. Reviews in urology, 6 Suppl 9(Suppl 9), S31–S39.

Thompson, I. M., Goodman, P. J., Tangen, C. M., Lucia, M. S., Miller, G. J., Ford, L. G., ... & Coltman Jr, C. A. (2003). The influence of finasteride on the development of prostate cancer. New England Journal of Medicine, 349(3), 215-224.

Thompson Jr, I. M., Goodman, P. J., Tangen, C. M., Parnes, H. L., Minasian, L. M., Godley, P. A., ... & Ford, L. G. (2013). Long-term survival of participants in the prostate cancer prevention trial. New England Journal of Medicine, 369, 603-610.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.