Health Library

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

When This Medicine Should Not Be Used:

How to Use This Medicine:

Tablet

• Your doctor will tell you how much medicine to use. Do not use more than directed.
• Swallow the tablet whole. Do not crush, break, or chew it. 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.
• Missed dose: 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.
• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

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:

• This medicine is not for use in women. Women who are pregnant should avoid touching or handling this medicine because it can harm an unborn male baby. If a pregnant woman gets this medicine on her skin, wash the area immediately with soap and water.
• Tell your doctor if you have liver disease.
• 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 increase your risk of high-grade prostate cancer.
• 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.
• Some men who use this medicine have become infertile (unable to have children). Talk with your doctor before using this medicine if you plan to have children.
• Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
• Keep all medicine out of the reach of children. Never share your medicine with anyone.

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, or lumps, nipple discharge
• Change in how much or how often you urinate
• Lightheadedness, dizziness, or fainting

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

• Decrease in the amount of semen
• Decrease or change in your sexual desire
• Trouble having or keeping an erection, other sexual problems
• 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: 9/6/2024