Finasteride (Propecia, Proscar) is a generic prescription medication used to treat the following conditions in adult males:*

Finasteride comes as an oral tablet. As with other drugs, finasteride can cause side effects (also called adverse effects).

If finasteride works for you, your doctor will likely recommend taking it long term.

Read on to learn about potential common, mild, and serious side effects. For a general overview of finasteride, including details about its uses, refer to this article. Your doctor can also tell you more about finasteride.

* Sex and gender exist on spectrums. Use of the term “male” in this article refers to sex assigned at birth.

Finasteride can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took finasteride in clinical trials:

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with finasteride use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to finasteride’s prescribing information.

Mild side effects that have been reported with finasteride include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking finasteride and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.

Finasteride may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to finasteride’s prescribing information.

If you develop serious side effects while taking finasteride, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

* For more information about this side effect, see “Side effect specifics” below.

Finasteride is approved to treat male pattern hair loss in adult males.*

Side effects when used for male and female hair loss

Side effects of finasteride when taken for male pattern hair loss and benign prostatic hyperplasia are similar. The most common side effects reported in males who took finasteride for hair loss include:

Finasteride is not approved for use in females* at this time. However, the drug may be used off-label in females for hair growth. Off-label drug use is when a drug that’s approved to treat one condition is prescribed to treat a different condition.

However, people who are pregnant should not touch finasteride tablets that are broken or crushed. This is because exposure to finasteride during pregnancy may increase the risk of congenital anomalies (commonly known as “birth defects”). For more information, see the “Pregnancy and breastfeeding while taking finasteride” section below.

* Sex and gender exist on spectrums. Use of the terms “female” and “male” in this article refers to sex assigned at birth.

Finasteride is approved to treat benign prostatic hyperplasia and male pattern hair loss in adult males.*

The most common side effects reported by males taking finasteride include:

At this time, finasteride isn’t approved for use in females.* So, it’s not known what side effects may occur in females taking finasteride.

However, finasteride may be used off-label in females. Off-label drug use is when a drug that’s approved to treat one condition is prescribed to treat a different condition.

* Sex and gender exist on spectrums. Use of the terms “female” and “male” in this article refers to sex assigned at birth.

Finasteride may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

What are the side effects of topical finasteride?

At this time, there isn’t a topical form of finasteride that’s FDA approved. So, it’s not known what side effects topical finasteride may cause. However, studies of the drug in topical forms, such as a topical spray, are currently ongoing. (A topical drug is a medication that you apply to your skin.)

One study shows that topical finasteride may have fewer systemic (whole-body) side effects than oral finasteride. For example, the risk of erectile dysfunction may be lower if you use the topical form of finasteride compared with the oral form of the drug.

However, more studies are needed to determine what the finasteride spray side effects or topical side effects may be. In addition, it’s possible for finasteride to be used in combination with other medications for hair loss, such as minoxidil (Rogaine). However, more information is needed to determine what the finasteride and minoxidil side effects may be.

If you have questions about different forms of finasteride, talk with your doctor or pharmacist.

How do side effects of 1-mg and 5-mg finasteride tablets compare?

Side effects of 1-milligram (mg) and 5-mg finasteride tablets will likely be similar. However, you may be at an increased risk of side effects if you’re taking a higher dose of medication. So, people taking 5-mg tablets of finasteride may have an increased risk of side effects than people taking the 1-mg tablets.

If you have questions or concerns about side effects of finasteride, talk with your doctor or pharmacist.

Are any side effects of finasteride long term or permanent?

Most side effects of finasteride are short term and can improve when you stop taking finasteride. However, it’s possible for this medication to cause long-term or permanent side effects. For example, prostate cancer or depression are side effects that may last after stopping treatment with finasteride.

If you’re concerned about finasteride causing long-term or permanent side effects, talk with your doctor or pharmacist.

Learn more about some of the side effects that finasteride may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for finasteride.

Erectile dysfunction

You may experience sexual side effects, such as erectile dysfunction (ED), from taking finasteride. This was a common side effect reported in clinical trials of the drug. ED can include difficulty getting or maintaining an erection.

What you can do

If you experience ED after starting treatment with finasteride, tell your doctor. They may be able to prescribe medications, such as sildenafil (Viagra), to treat your ED.

Post-finasteride syndrome

It’s possible to experience side effects after stopping treatment with finasteride. This may be referred to as post-finasteride syndrome. Though post-finasteride syndrome wasn’t reported during clinical trials of finasteride, it did occur in studies after the drug was approved for use.

Post-finasteride syndrome may occur if you’re taking the drug to treat benign prostatic hyperplasia or male pattern hair loss. Symptoms of post-finasteride syndrome may include:

What you can do

If you need to stop treatment with finasteride for any reason, be sure to talk with your doctor first. They can help determine the safest way for you to stop treatment. In addition, they may be able to recommend another treatment option for you.

After you stop finasteride, your doctor may monitor you for symptoms of post-finasteride syndrome. They may be able to treat any symptoms that you experience from this condition.

If you’re concerned about post-finasteride syndrome from stopping finasteride, talk with your doctor or pharmacist. They can help determine the best way for you to stop treatment.

Decreased libido

It’s possible for finasteride to decrease your libido. This means you may notice that your sex drive is lower than usual.

Decreased libido was a common side effect of finasteride reported in clinical trials.

What you can do

If you notice a decreased libido from taking finasteride, talk with your doctor. In some cases, they may be able to recommend ways to manage this side effect. Other times, they may recommend a different treatment option for your condition.

Allergic reaction

As with most drugs, finasteride can cause an allergic reaction in some people. Though allergic reaction wasn’t seen in clinical trials, it is possible. Allergic reaction was reported in people taking finasteride after the drug was approved for use.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking finasteride. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

  • Ask the tough question: “Are you considering suicide?”
  • Listen to the person without judgment.
  • Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
  • Stay with the person until professional help arrives.
  • Try to remove any weapons, medications, or other potentially harmful objects.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Click here for more links and local resources.

Be sure to talk with your doctor about your health history before you take finasteride. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. These are considered drug-condition or drug-factor interactions. The conditions and factors to consider include:

Allergic reaction. If you’ve had an allergic reaction to finasteride or any of its ingredients, your doctor will likely not prescribe finasteride. Taking finasteride could cause you to have another allergic reaction. Ask your doctor what other medications may be better options for you.

Liver problems. If you have liver problems, be sure to tell your doctor before starting treatment with finasteride. This medication is removed from your body by your liver. And if you have liver problems, you may be at an increased risk of side effects from finasteride. Examples of these side effects can include erectile dysfunction and depression. If you have liver problems, your doctor can help determine whether it may be safe for you to take finasteride.

Alcohol with finasteride

There aren’t any known interactions between finasteride and alcohol.

However, it’s possible that drinking alcohol can increase your risk of side effects from finasteride. For example, alcohol can increase your risk of sexual problems, such as erectile dysfunction. Since finasteride may also cause this side effect, drinking alcohol may increase this risk.

If you would like to drink alcohol while you’re taking finasteride, talk with your doctor to see how much, if any, is safe to consume.

Pregnancy and breastfeeding while taking finasteride

Finasteride is not safe to take during pregnancy. It isn’t known if the drug is safe to take while breastfeeding. However, this medication isn’t approved for use in females* at this time.

In animal studies, finasteride caused congenital anomalies (also known as birth defects) in the development of male offspring. Specifically, exposure to finasteride caused genital abnormalities. However, it’s important to note that animal studies don’t always indicate what may happen in humans.

If you’re pregnant, you should not touch finasteride tablets that are broken or crushed. This is because exposure to finasteride during pregnancy may increase the risk of congenital anomalies (birth defects). If you’re pregnant and you come into contact with a broken or crushed finasteride tablet, wash the area with soap and water right away.

However, it’s safe to touch finasteride tablets that aren’t broken or crushed. This is because the tablets have a coating on them that protects the drug from being absorbed into your skin.

It’s not known whether finasteride is safe to take while breastfeeding. It isn’t known whether the drug passes into breast milk or what effects the drug may have on a breastfed child.

If you’re pregnant, planning to become pregnant, or breastfeeding, talk with your doctor before taking finasteride.

* Sex and gender exist on spectrums. Use of the terms “female” and “male” in this article refers to sex assigned at birth.

Finasteride may cause side effects, but most of them are mild. If you’d like to learn more about finasteride, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug. Referring to the following articles can provide you with additional information:

  • More information about finasteride. For details about other aspects of finasteride, refer to this article.
  • Cost. If you’d like to learn about finasteride and cost, see this article.
  • A look at prostate health. For information about prostate health, see our men’s health hub.

Disclaimer: Medical News Today 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 another healthcare professional before taking any medication. The drug information contained herein 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.