A man’s prostate continues to grow throughout his lifetime. For some men, their prostate becomes so large that it begins to cause problems. This is a condition called benign prostatic hyperplasia (BPH). BPH is more commonly know as enlarged prostate. This condition typically develops in older men. Men with BPH may have symptoms such as the need to urinate more often, difficulty starting a urine stream, or decreased urine flow.

Drugs that treat BPH belong to a class called 5alpha-reductase inhibitors. Dutasteride and finasteride are two popular 5alpha-reductase inhibitors that are used to treat BPH. These drugs prevent male hormones from increasing the size of your prostate. You generally need to have been taking one of these drugs for at least 6 months before your BPH symptoms improve.

Dutasteride and finasteride are very similar drugs. The following table lists their features.

Usetreatment of benign prostatic hyperplasiatreatment of benign prostatic hyperplasia*
Is a generic version available?yesyes
Strength0.5 mg 5 mg
How do I take it?by mouthby mouth
How often do I take it?once dailyonce daily
Do I take it for long-term or short-term treatment?long term**long term**
How do I store it?between 68°F and 77°F (20°C and 25°C)between 68°F and 77°F (20°C and 25°C)
*Finasteride can also be used to treat male pattern hair loss.
**Treatment usually continues for the rest of your life.

Availability and insurance

Insurance companies sometimes cover only one drug in a class. Finasteride may be preferred for coverage over dutasteride by some insurance companies. Both of these drugs are commonly available at most pharmacies.


Both dutasteride and finasteride treat BPH well. The effectiveness is similar between the two drugs.

Read more: Detailed information about dutasteride, including dosage, warnings, cost, and more »

Dutasteride and finasteride have the same side effects. These side effects are listed in the following table:

Common side effects• impotence (trouble getting or keeping an erection)
• ejaculation disorders
• decreased sexual drive
• breast enlargement or tenderness
• impotence (trouble getting or keeping an erection)
• ejaculation disorders
• decreased sexual drive
• breast enlargement or tenderness
Serious side effects• increased risk of certain types of prostate cancer*• increased risk of certain types of prostate cancer*
*This is rare.


An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well. Finasteride does not have any known drug interactions. Dutasteride can interact with the following drugs:

  • certain HIV drugs, such as ritonavir
  • certain blood pressure and angina drugs, such as amlodipine
  • certain antibiotics, such as azithromycin

Taking any of these drugs with dutasteride may slow how your liver breaks down dutasteride. This can cause more of the drug to stay in your body than usual. However, this interaction has not been proved to increase your risk of side effects from dutasteride.

Read more: Detailed information about finasteride, including dosage, warnings, cost »

Risks to pregnant or breastfeeding women

Dutasteride and finasteride can harm a developing fetus. Women who are pregnant should avoid these drugs.

These drugs can absorb through your skin when you handle them. Women who are pregnant should not handle them. Women who do touch a dutasteride capsule or a finasteride tablet should wash their hands immediately with soap and water.

Men who take this drug should take precautions not to transfer it. Men who take dutasteride should wait 6 months after their last dose to donate blood. Finasteride leaves your body a lot more quickly, so men who take finasteride should wait 72 hours after their last dose to donate blood. Waiting these periods can help you avoid exposing pregnant women to either drug if they receive your blood.

Your doctor can tell you more about dutasteride and finasteride. Talk to them about this article and ask any questions you may have. Your doctor knows your medical history and can help you decide on a treatment that’s both effective and appropriate for your specific health needs.