Health Guide

Finasteride (By mouth)

Finasteride (fin-AS-ter-ide)

Treats benign prostatic hyperplasia (enlarged prostate). Also treats hair loss in men.

Brand Name(s):

Propecia, Proscar

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

You should not use this medicine if you have had an allergic reaction to finasteride. Women and children should not use this medicine.

How to Use This Medicine:


  • Your doctor will tell you how much medicine to use. Do not use more than directed.
  • You may take this medicine with or without food.
  • Take this medicine at the same time each day.
  • For hair loss, you may need to take this medicine for 3 months or longer before you see an effect.
  • For an enlarged prostate, you may need to take this medicine for up to 6 months to see the full effect.
  • Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.

If a dose is missed:

  • If you miss a dose or forget to take your medicine, skip the missed dose and take your next regular dose. Do not use extra medicine to make up for a missed dose.

How to Store and Dispose of This Medicine:

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

Warnings While Using This Medicine:

  • Women who are pregnant or may become pregnant should avoid handling or touching this medicine. This medicine can get into the body through the skin and may harm an unborn male baby. If any of this medicine gets on the skin of a woman, wash the area immediately with soap and water.
  • Make sure your doctor knows if you have liver disease or severe problems urinating.
  • This medicine will not cure an enlarged prostate problem or male pattern baldness. Once you stop using this medicine, the prostate will begin to grow again within a few months and any new hair will be lost within 12 months.
  • This medicine may cause changes to the breast tissue. Tell your doctor if you have any lumps, pain, tenderness, or an enlargement of the breasts while using this medicine.
  • This medicine will not prevent prostate cancer but may increase your risk of developing high-grade prostate cancer. Tell your doctor if you have concerns about this risk.
  • This medicine may affect the results of the prostate specific antigen (PSA) test, which may be used to detect prostate cancer. Make sure you tell all of your doctors that you are using this medicine.
  • This medicine may cause a decrease in the amount of semen you ejaculate during sex. This will not affect your sperm count or your ability to have children.
  • Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments. Blood tests may be needed to check for unwanted effects.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Breast swelling, pain, or tenderness.
  • Lightheadedness, dizziness, or fainting.
  • Lumps in the breast or under the arm.
  • Pain in the testicles.
  • Swelling in your hands, ankles, or feet.

If you notice these less serious side effects, talk with your doctor:

  • Decrease in the amount of semen.
  • Loss of interest in sex or the ability to have sex (impotence).
  • Skin rash.
  • Sleepiness or unusual drowsiness.
  • Stuffy or runny nose.
  • Trouble having or keeping an erection.
  • Weakness.

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 6/18/2019
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