Finasteride, Oral Tablet

Medically reviewed by University of Illinois-Chicago, Drug Information Group on February 15, 2017Written by University of Illinois-Chicago, Drug Information Group

Important warnings

  • Pregnancy contact warning: Women who are pregnant or planning to become pregnant shouldn’t handle crushed or broken finasteride tablets. Contact with this drug, even through the skin, by these women could lead to defects in developing male fetuses.
  • Prostate cancer warning: This drug belongs to a class of drugs that could increase your risk of a faster growing or irregular form of prostate cancer. Finasteride can cause a decrease in your prostate specific antigen (PSA) level. An increased level of this antigen has been associated with prostate cancer. If your PSA levels increase while on this medication, it may be a sign of prostate cancer.

What is finasteride?

Finasteride is a prescription drug. It comes as an oral tablet.

Finasteride oral tablet is available as the brand-name drugs Proscar and Propecia. It’s also available as a generic drug. Generic drugs usually cost less than the brand-name version. In some cases, they may not be available in every strength or form as the brand-name drug.

Why it's used

The condition that finasteride is used to treat depends on the type of the drug used.

  • Proscar is used to treat the symptoms of enlarged prostate (benign prostate hyperplasia). It may be used as part of a combination therapy. That means you need to take it with other drugs. It also can be taken with doxazosin to reduce the risk of progression of symptoms of enlarged prostate.
  • Propecia and the generic form of finasteride are used to treat male pattern hair loss.

Finasteride isn’t prescribed for use in women or children.

How it works

Finasteride works by decreasing the amount of the hormone dihydrotestosterone (DHT) in your body. DHT normally causes your prostate to grow larger.

The decrease in DHT helps prevent your prostate from growing larger. It also leads to increased hair growth and decreased hair loss of the hair on your head. Hair growth on other parts of the body isn’t affected.

Finasteride side effects

Finasteride oral tablet doesn’t cause drowsiness, but it can cause other side effects.

More common side effects

The more common side effects that can occur with finasteride include:

  • decreased sex drive
  • trouble getting or keeping an erection
  • ejaculation disorder
  • increase in breast size and tenderness
  • skin rash

If these effects are mild, they may disappear within a few days or a couple of weeks. If they’re more severe or don’t disappear, talk to your doctor or pharmacist.

Serious side effects

Call your doctor right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • swelling of your lips, tongue, throat, or face
  • depression
  • lumps or pain in your breasts
  • nipple discharge

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we can not guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.

Finasteride may interact with other medications

An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well. To help prevent interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking.

To find out how finasteride oral tablet might interact with something else you’re taking, talk to your doctor or pharmacist.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we can not guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.

Finasteride warnings

This drug comes with several warnings.

Allergy warning

Finasteride can cause a severe allergic reaction, causing symptoms such as:

  • trouble breathing
  • swelling of your throat or tongue
  • hives

If you develop these symptoms, call 911 or go to the nearest emergency room.

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal (cause death).

Contact with drug warning

Finasteride may be passed through the skin. Pregnant women and women who plan to become pregnant in the near future shouldn’t handle this drug. Doing so could cause birth defects.

Warnings for people with certain health conditions

For people with liver disease: This drug is processed in your liver. If you have liver disease, your body might process this drug more slowly. This could lead to a buildup of this drug in your body, which could increase your risk of side effects. Your doctor might reduce your dosage of finasteride.

For people with prostate cancer: Finasteride can increase the chance of a faster growing or irregular form of prostate cancer. If you have or have had prostate cancer, this drug can make it worse.

Warnings for other groups

For pregnant women: Finasteride is a category X pregnancy drug. Category X drugs should never be used during pregnancy.

This drug is not prescribed for use in women.

For women who are breastfeeding: Finasteride should never be used in breastfeeding women. It isn’t known if finasteride passes through breast milk.

This drug is not prescribed for use in women.

For children: The safety and effectiveness of finasteride in children haven’t been established. This drug is not prescribed for use in children.

How to take finasteride

All possible dosages and forms may not be included here. Your dose, form, and how often you take it will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

Dosage for male pattern hair loss

Generic: Finasteride

  • Form: oral tablet
  • Strengths: 1 mg

Brand: Propecia

  • Form: oral tablet
  • Strengths: 1 mg

Adult dosage (ages 18 years and older)

  • Typical dosage: 1 mg per day.

Child dosage (ages 0-17 years)

Dosage for people younger than 18 years hasn’t been established. This drug is not prescribed for use in children.

Dosage for benign prostatic hyperplasia

Brand: Proscar

  • Form: oral tablet
  • Strengths: 5 mg

Adult dosage (ages 18 years and older)

  • Typical dosage: 5 mg per day.

Child dosage (ages 0–17 years)

Dosage for people younger than 18 years hasn’t been established. This drug is not prescribed for use in children.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we can not guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always speak with your doctor or pharmacist about dosages that are right for you.

Take as directed

Finasteride is used for long-term treatment. It comes with serious risks if you don't take it as prescribed.

If you don't take it at all: You may not see improvement in your condition. If you’re taking this drug for BPH, you may not see an improvement in your BPH symptoms. If you’re taking it for male pattern hair loss, you may not see an improvement in hair loss and hair regrowth.

If you take too much: If you take too much, you’re at a higher risk of developing negative reactions. These can include decreased sex drive, trouble getting or keeping an erection, ejaculation disorder, increase in breast size or tenderness, and rash.

What to do if you miss a dose: If you forget to take your dose, do not take an extra tablet. Just take the next tablet as usual.

How to tell if the drug is working: If you’re taking this drug for BPH, you may notice a decreased urge to urinate and improved urine flow. You should also have a decrease in the feeling that your bladder isn’t completely emptied after you urinate. If you’re taking this drug for male pattern hair loss, you may notice less hair loss and more hair growth on your head.

Important considerations for taking finasteride

Keep these considerations in mind if your doctor prescribes finasteride for you.

General

  • Don’t crush, cut, or chew the tablets.

Storage

  • Store finasteride at room temperature between 59°F and 86°F (15°C and 30°C).
  • Keep it away from light and high temperature.
  • Don’t store this medication in moist or damp areas, such as bathrooms.

Refills

A prescription for this medication is refillable. You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t harm your medication.
  • You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled container with you.
  • Don’t put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Clinical monitoring

Your doctor will monitor your prostate specific antigen (PSA) levels while you’re taking finasteride.

Prior authorization

If you’re taking this drug for male pattern hair loss, your insurance company may need a prior authorization before they approve the prescription and pay for finasteride. Approval is determined on a plan-by-plan basis.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained here in is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

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