Avodart (Dutasteride)

How does it work?

Avodart capsules contain the active ingredient dutasteride, which is a type of medicine called a 5-alpha reductase inhibitor.

Dutasteride works by inhibiting the action of a compound in the body called 5-alpha reductase. This compound is called an enzyme, and is responsible for converting the male hormone testosterone into dihydrotestosterone (DHT), which is a more active form of testosterone.

The enlargement of the prostate gland, (known medically as benign prostatic hyperplasia), which often occurs in men with advancing age, is dependent upon testosterone being converted to DHT within the prostate gland. In the absence of DHT the prostate gland shrinks. By decreasing the amount of testosterone that is converted into DHT, dutasteride therefore helps to shrink the prostate gland.

The prostate gland is found only in men and lies at the top of the tube connecting the bladder to the outside (urethra). Enlargement of the prostate causes it to press on the urethra and bladder and can cause urinary symptoms such as difficulty passing urine and increased need to urinate, particularly at night. By shrinking the prostate, dutasteride relieves the pressure on the bladder and urethra. This allows urine to flow freely past the prostate and relieves the urinary symptoms associated with this condition.

Dutasteride is used to relieve moderate to severe symptoms of BPH and to reduce the risk of developing a complete inability to pass urine (acute urinary retention) that may require surgery.

You may see an improvement in your symptoms soon after starting treatment with this medicine, but most men will need to take it for at least six months to see if it helps.

What is it used for?

  • Enlarged prostate gland (benign prostatic hyperplasia).

Avodart is used to relieve moderate to severe symptoms of BPH and to reduce the risk of developing a complete inability to pass urine (acute urinary retention) that may require surgery.

How do I take it?

  • One Avodart capsule should be taken once a day, preferably at the same time each day. The capsule can be taken either with or without food.
  • The capsules should be swallowed whole and not chewed or opened, because the contents of the capsule may irritate the lining of the mouth and throat.


  • This medicine does not cause prostate cancer, but prostate cancer can be another cause of an enlarged prostate gland. For this reason, tests for prostate cancer should be carried out before you start treatment with this medicine, and at regular intervals thereafter. One test that can be carried out is a digital rectal examination (DRE), to check if the prostate gland is enlarged. The other is to measure the level of prostate specific antigen (PSA) in the blood. An increase in the PSA levels may mean that the prostate gland is enlarged. This medicine can decrease the amount of PSA in the blood by about 50 per cent after six months treatment, even in men who have prostate cancer. Your doctor will take this into account when interpreting the results of any blood tests.
  • This medicine has been reported to affect semen characteristics (reduction in sperm count, semen volume, and sperm motility) in healthy men. This means that there is a possiblity that it may therefore reduce your fertility and ability to father a child. If this is a concern to you, you should discuss fertility with your doctor before starting treatment.
  • While you are taking this medicine you should use a condom during sex if your sexual partner is pregnant or could become pregnant. This is because the active ingredient of this medicine passes into semen, and could harm the development of a male baby.
  • Dutasteride can be absorbed through the skin and for this reason women, children and adolescents should avoid contact with any capsules of this medicine that are leaking. If contact is made with leaking capsules, the contact area should be washed immediately with soap and water.

Use with caution in

  • Mild to moderately decreased liver function.

Not to be used in

  • Women.
  • Children or adolescents under 18 years of age.
  • Allergy to other 5-alpha reductase inhibitors, eg finasteride.
  • Allergy to soya or peanuts.
  • Severely decreased liver function.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

  • This medicine is for use by men only, therefore information about its use by pregnant or breastfeeding women is not applicable. However, this medicine may pass into semen. For this reason, men whose partner is or may be pregnant should use a barrier form of contraception such as a condom during sex, to avoid any possible risks to a developing male baby.

Label warnings

  • This medication is to be swallowed whole, not chewed.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

  • Difficulty achieving or maintaining an erection (impotence).
  • Decreased sex drive.
  • Ejaculation disorders, such as decreased amount of semen produced or decreased sperm count.
  • Breast enlargement or tenderness.
  • Allergic reactions such as rash, itching or localised swelling.
  • Dizziness.
  • Hair loss (primarily body hair) or increased hair growth.

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer. For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.

The following medicines may increase the level of dutasteride in the blood by interfering with its breakdown by the body:

  • diltiazem
  • indinavir
  • itraconazole
  • ketoconazole taken by mouth
  • nefazodone
  • ritonavir
  • verapamil.

Let your doctor know if you experience any new or increased side effects if you are taking any of these medicines in combination with dutasteride. Your doctor may ask you to take the dutasteride less frequently to resolve this.

Other medicines containing the same active ingredient

There are currently no other medicines available in the UK that contain dutasteride as the only active ingredient.

Combodart contains dutasteride in combination with another medicine called tamsulosin, which is also used to treat symptoms of an enlarged prostate gland.