Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

1. Propecia
2. Proscar

Descriptions

Note: Women who are pregnant or may become pregnant should not use finasteride or handle the crushed or broken tablets. Finasteride can cause birth defects in male babies.

Finasteride is used to treat men who have symptoms of benign prostatic hyperplasia (BPH) and male pattern hair loss, also called androgenetic alopecia. BPH is caused by an enlarged prostate. Men with BPH usually have difficulty urinating, a decreased flow of urination, hesitation at the beginning of urination, and a need to get up at night to urinate. Finasteride will make these symptoms less severe and reduce the chance that prostate surgery will be needed. It may be used alone or in combination with other medicines such as an alpha-blocker (doxazosin, Cardura®) to treat BPH. For men with hair loss, finasteride will increase the number of scalp hairs but will not increase the amount of body hair.

Finasteride blocks the action of an enzyme called 5-alpha-reductase. This enzyme changes testosterone to another hormone that causes the prostate to grow. It will increase testosterone levels in the body, which decreases prostate size. The effect of finasteride will only last as long as the medicine is taken.

This medicine is available only with your doctor's prescription.

This product is available in the following dosage forms:

• Tablet

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Finasteride is not indicated for use in the pediatric population. Safety and efficacy have not been established.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of finasteride in the elderly.

Breastfeeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• St John's Wort

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Liver disease—Use with caution. The effects may be increased because of slower removal of the medicine from the body.

Proper Use

Take this medicine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

This medicine comes with a patient information leaflet. Read and follow the instructions carefully. Ask your doctor if you have any questions.

You may take this medicine with or without food.

If you are taking this medicine for male pattern hair loss, it may take at least 3 months to see an effect. The medicine will not cure hair loss, but it will cause scalp hair to grow. The hair growth will only last as long as the medicine is used. The new hair will be lost within 1 year after the medicine is stopped.

If you are taking this medicine for benign prostatic hyperplasia (BPH), it may take up to 6 months to see the full effect. The medicine will not cure BPH, but it does help reduce the size of the prostate and improve symptoms. The effect on the prostate will only last as long as the medicine is used. When it is stopped, the prostate begins to grow again within a few months.

Swallow the tablet whole. Do not crush, break, or chew it. Take this medicine at the same time each day.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage form (tablets):
  • For benign prostatic hyperplasia:
    • Adults—5 milligrams (mg) once a day.
    • Children—Use is not recommended.
  • For male pattern hair loss:
    • Adults—1 milligram (mg) once a day.
    • Children—Use is not recommended.

Missed Dose

If you miss a dose of this medicine, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions

It is very important that your doctor check your progress at regular visits. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it. Blood and urine tests may be needed to check for unwanted effects.

Women and children should not use this medicine. Women who are pregnant or may become pregnant should not handle crushed or broken tablets. Finasteride can be absorbed through the skin and cause birth defects in male babies. If a woman does come in contact with this medicine, the affected area should be washed right away with soap and water.

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.

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.

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

1. Chills
2. cold sweats
3. confusion
4. dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position

Less common

1. Bloating or swelling of the face, arms, hands, lower legs, or feet
2. breast enlargement and tenderness
3. hives or welts, itching, skin rash
4. rapid weight gain
5. redness of the skin
6. swelling of the lips and face
7. tingling of the hands or feet
8. unusual weight gain or loss

Incidence not known

1. Clear or bloody discharge from the nipple
2. dimpling of the breast skin
3. inverted nipple
4. lump in the breast or under the arm
5. persistent crusting or scaling of the nipple
6. redness or swelling of the breast
7. sore on the skin of the breast that does not heal

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

1. Decreased interest in sexual intercourse
2. inability to have or keep an erection
3. loss in sexual ability, desire, drive, or performance

Less common

1. Runny or stuffy nose
2. sleepiness or unusual drowsiness
3. sneezing

Less common or rare

1. Back pain
2. decreased amount of semen
3. diarrhea
4. dizziness
5. headache
6. stomach pain

Incidence not known

1. Testicular pain

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

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

Portions of this document last updated: Feb. 01, 2024

Original article: https://www.mayoclinic.org/es-es/drugs-supplements/finasteride-oral-route/before-using/drg-20063819