If you have breast cancer, your doctor might prescribe Femara for you.

It’s a prescription drug that’s used to treat certain types of breast cancer in adult females* who have gone through menopause. The types include:

To learn more about these conditions and how Femara is used to treat them, see the “What is Femara used for?” section below.

* In this article, we use the term “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

Femara basics

Femara comes as tablets that you take by mouth.

Femara contains the active drug letrozole and is available as a generic drug called letrozole. Femara is classified as an aromatase inhibitor. (A drug class is a group of medications that work in a similar way.)

Read on to learn how to take Femara, what its uses and side effects are, and more.

Like most drugs, Femara may cause mild or serious side effects. The lists below describe some of the more common side effects that Femara may cause. These lists don’t include all possible side effects.

Keep in mind that side effects of a drug can depend on:

  • your age
  • other health conditions you have
  • other medications you may be taking

Your doctor or pharmacist can tell you more about the potential side effects of Femara. They can also suggest ways to help reduce side effects.

Mild side effects

Here’s a list of some of the mild side effects that Femara can cause. To learn about other mild side effects, talk with your doctor or pharmacist, or read Femara’s prescribing information.

Mild side effects of Femara that have been reported include:

Mild side effects of many drugs may go away within a few days or a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

* For more information on this side effect, see the “Side effect focus” section below.

Serious side effects

Serious side effects from Femara can occur, but they aren’t common. If you have serious side effects from Femara, call your doctor right away. However, if you think you’re having a medical emergency, you should call 911 or your local emergency number.

Serious side effects of Femara that have been reported include:

* For more information on this side effect, see the “Side effect focus” section below.

Side effect focus

Learn more about some of the side effects Femara may cause.

Weight gain

Weight gain was a common side effect in studies of Femara.

You may also gain weight if you have swelling, which is another possible side effect of Femara. Swelling from Femara usually occurs in your arms, feet, hands, or legs.

What might help

If you’re concerned about weight gain while taking Femara, talk with your doctor. They can recommend healthy ways for you to manage your weight.

Headache

Headaches were a common side effect in studies of Femara.

What might help

Over-the-counter (OTC) medications, such as acetaminophen (Tylenol) and ibuprofen (Advil), may be effective for relieving headaches. But make sure you talk with your doctor or pharmacist before taking any new medications with Femara.

You may also be able to ease headaches by applying an ice pack or heating pad to your head. You can do this for about 10 minutes a few times each day. A hot shower or bath may also provide some headache relief.

Spotting

Spotting may occur with Femara use. Spotting refers to slight vaginal bleeding when you aren’t having your period. This was common in clinical studies of the drug.

Spotting may occur along with other side effects from Femara, such as belly pain or cramping.

What might help

Talk with your doctor if you have bothersome spotting while taking Femara. They can suggest ways to help manage this side effect.

Allergic reaction

Some people may have an allergic reaction to Femara. Although allergic reaction wasn’t reported in studies of Femara, it can still happen.

Symptoms of a mild allergic reaction can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include swelling under your skin, typically in your eyelids, lips, hands, or feet. They can also include swelling of your tongue, mouth, or throat, which can cause trouble breathing.

Call your doctor right away if you have an allergic reaction to Femara. But if you think you’re having a medical emergency, call 911 or your local emergency number.

Find answers to some commonly asked questions about Femara.

Is Femara used for infertility?

Femara isn’t currently approved to treat infertility in females.* However, the drug may be used off-label for this purpose. (Off-label use means using a drug for a condition other than the one it’s approved to treat.)

Female infertility refers to not being able to become or stay pregnant. Infertility is often caused by problems with ovulation (when eggs are released from your ovaries). And ovulation problems commonly happen because of a condition called polycystic ovary syndrome (PCOS). Femara may be used off-label to treat infertility due to PCOS and other causes.

If you have questions about using Femara to treat infertility, talk with your doctor.

* In this article, we use the term “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

What should I know about Femara versus Clomid?

Clomid was a brand-name drug that’s no longer available. But a generic version called clomiphene is available. Both Femara and clomiphene may be prescribed to treat female* infertility.

Femara isn’t currently approved to treat infertility in females. However, the drug may be used off-label for this purpose. (To learn more, see “Is Femara used for infertility?” right above.) Clomiphene is approved to treat infertility in females.

Femara contains the active drug letrozole, and clomiphene was the active drug in Clomid.

Femara and clomiphene are both used to stimulate ovulation in females who are having trouble becoming pregnant.

If you have more questions about how Femara and clomiphene are alike and different, talk with your doctor.

* In this article, we use the term “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

Is Femara a chemotherapy drug?

No, Femara isn’t a form of chemotherapy. Femara is a kind of hormone therapy.

Chemotherapy is a type of cancer drug. It works by killing cells in your body that multiply quickly. Cancer cells usually increase in number more quickly than healthy cells. But some healthy cells in the body also quickly multiply. So, chemotherapy can affect both healthy cells and cancer cells.

Femara is a kind of drug called an aromatase inhibitor. As a type of hormone therapy, Femara works by lowering estrogen levels in your body. This helps stop breast cancer from growing.

Will I have side effects after stopping Femara treatment?

It’s possible you may have side effects after stopping Femara treatment.

Femara can stay in your system for several weeks after your last dose. So, side effects that you have while taking Femara may continue for a few weeks after you stop using it.

Most people will take Femara to treat their breast cancer for at least 5 years. If you’re concerned about side effects from stopping Femara treatment after 5 years, talk with your doctor.

How does Femara work? And what’s its half-life?

Femara belongs to a group of drugs called aromatase inhibitors. The drug works by lowering estrogen levels in your body, which helps stop breast cancer from growing.

The half-life of Femara is about 2 days. The half-life is the amount of time it takes for the drug level in your body to decrease by half. In other words, it takes about 2 days for your body to get rid of half of a Femara dose.

What is Femara’s success rate in treating cancer?

Femara has been found effective for treating certain types of breast cancer. For information on how Femara performed in clinical studies, see the drug’s prescribing information.

If you have questions about Femara’s success rate in treating cancer, talk with your doctor.

Is Femara approved for use in bodybuilding? If so, what’s the dosage used?

No, the Food and Drug Administration (FDA) hasn’t approved Femara for use in bodybuilding.

Femara is FDA-approved to treat only certain types of breast cancer. You shouldn’t take Femara unless it’s been prescribed by a healthcare professional. You also shouldn’t use the drug for conditions it hasn’t been prescribed to treat.

If you have questions about using Femara, talk with your doctor.

Costs of prescription drugs can vary depending on many factors. These factors include what your insurance plan covers and which pharmacy you use. To find current prices for Femara tablets in your area, visit GoodRx.com.

If you have questions about how to pay for your prescription, talk with your doctor or pharmacist. You can also visit the Femara manufacturer’s website to see if there are support options.

Your doctor will explain how you should take Femara, such as how much to take and how often. Be sure to follow your doctor’s instructions. Below are commonly used dosages, but always take the dosage your doctor prescribes.

Taking Femara

Femara comes as tablets that you take by mouth.

Femara tablets come in one strength: 2.5 milligrams (mg).

Dosage

The standard Femara dosage is the same for all types of breast cancer the drug is used to treat. This dosage is 1 tablet once daily.

Taking Femara with other drugs

Your doctor may prescribe Femara along with other breast cancer treatments.

They may recommend that you take Femara after you’ve had surgery to remove early breast cancer.With early breast cancer, the cancer hasn’t spread beyond your breast or the lymph nodes in your armpit.

In some cases, your doctor may prescribe Femara after you’ve taken tamoxifen for your cancer for at least 5 years. When used for this purpose, Femara helps lower the risk of your cancer coming back.

If you have questions about taking Femara with other drugs, talk with your doctor.

Questions about taking Femara

Here are some common questions about taking Femara tablets.

  • What if I miss a dose of Femara? Take your missed dose as soon as you remember. If it’s almost time for your next dose, skip your missed dose. Then take your next dose at its regular time. If you aren’t sure whether to take a missed dose or skip it, talk with your doctor or pharmacist.
  • Will I need to use Femara long term? You may need to take Femara long term. If your breast cancer gets worse or you aren’t able to tolerate Femara’s side effects, your doctor may have you stop taking it. Most people take this drug for at least 5 years. But your doctor will prescribe Femara for the length of time that’s right for you.
  • Can Femara be chewed, crushed, or split? No, you shouldn’t chew, crush, or split Femara tablets. You should swallow them whole. If you have trouble swallowing Femara tablets, talk with your doctor or pharmacist.
  • Should I take Femara with food? You can take Femara with or without food.
  • How long does Femara take to work? Femara starts working right away to treat your breast cancer. But you probably won’t notice the drug working in your body. Your doctor will monitor your condition to see whether the drug is working for you.
Questions for your doctor

You may have questions about Femara and your treatment plan. It’s important to discuss all of your concerns with your doctor.

Here are a few tips that might help guide your discussion:

  • Before your appointment, write down questions such as:
    • How will Femara affect my body, mood, or lifestyle?
  • Bring someone with you to your appointment if doing so will help you feel more comfortable.
  • If you don’t understand something related to your condition or treatment, ask your doctor to explain it to you.

Remember, your doctor and other healthcare professionals are available to help you. And they want you to get the best care possible. So, don’t be afraid to ask questions or offer feedback on your treatment.

Femara is prescribed to treat certain types of breast cancer in adult females* who have gone through menopause.

Breast cancer occurs when breast cells grow rapidly and out of control. Breast cancer cells may form a tumor in the breast and spread to other areas of the body.

Below are brief descriptions of each type of breast cancer Femara is used to treat:

  • Early breast cancer that’s hormone receptor-positive (HR+). With early breast cancer, the cancer hasn’t spread beyond your breast or the lymph nodes in your armpit. With HR+ breast cancer, hormones cause the growth of cancer.
    • For this purpose, Femara is usually used to help lower the risk of the cancer coming back after it’s been removed by surgery.
  • Early breast cancer that’s been treated with surgery and tamoxifen. Tamoxifen is another breast cancer drug.
    • For this purpose, tamoxifen must have been used for at least 5 years. Femara is used to lower the risk of the cancer coming back.
  • Advanced or metastatic breast cancer that’s HR+ or the HR status isn’t known. With advanced breast cancer, the cancer has spread to areas of your body near your breast or the lymph nodes in your armpit. Metastatic breast cancer is cancer that has spread outside of areas near your breast or the lymph nodes in your armpit. The HR status may not be known because it hasn’t been tested.
  • Advanced breast cancer that has spread after a certain treatment.
    • For this purpose, Femara is used after treatment with another breast cancer drug that blocks estrogen.

* In this article, we use the term “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

Before taking Femara, it’s important to talk with your doctor about your overall health and other medical conditions you have.

These and other important considerations are discussed in more detail below.

Interactions

Taking medications, vaccines, foods, and other things with a certain drug can affect how the drug works. These effects are called interactions.

Before taking Femara, be sure to tell your doctor about all medications you take, including prescription and over-the-counter types. Also describe any vitamins, herbs, or supplements you use. Your doctor or pharmacist can tell you about any interactions these items may cause with Femara.

Interactions with drugs or supplements

Femara can interact with several types of drugs. This includes the breast cancer medication tamoxifen.

In addition, drugs and other products that contain estrogen, such as vaginal creams, may decrease the effects of Femara.

Talk with your doctor or pharmacist if you’re taking tamoxifen or any products that have estrogen in them.

Warnings

Femara may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take Femara. Factors to consider include those in the list below.

  • High cholesterol. Femara can cause high cholesterol. Tell your doctor if you already have high cholesterol before taking the drug. During Femara treatment, your doctor will give you cholesterol tests from time to time. If your cholesterol levels get too high, your doctor may prescribe a drug to lower them.
  • Liver problems. Tell your doctor if you have any liver problems, such as cirrhosis, before starting Femara treatment. Liver problems can raise the level of Femara in your body and increase your risk for side effects. Your doctor may give you a low dose of Femara if you have liver problems.
  • Osteoporosis. Before taking Femara, tell your doctor if you have osteoporosis. Osteoporosis is a condition that causes thin or weak bones. Femara can also cause weakened bones. During Femara treatment, your doctor may give you a bone mineral density test. This will check the strength of your bones. If your bones are weak, you may need to take other drugs to help protect them while using Femara.
  • Allergic reaction. If you’ve had an allergic reaction to Femara or any of its ingredients, you shouldn’t take Femara. Ask your doctor what other medications are better options for you.

Femara and alcohol

It should be safe to drink alcohol during your Femara treatment.

However, alcohol can cause side effects similar to those of Femara. If you drink alcohol while taking Femara, you may be at a higher risk for these side effects, which can include:

If you drink alcohol, talk with your doctor about the amount that’s safe for you while taking Femara.

Pregnancy and breastfeeding

You shouldn’t use Femara while pregnant or breastfeeding. And you shouldn’t become pregnant or breastfeed for at least 3 weeks after your last dose of the drug.

If you’re pregnant or thinking about becoming pregnant, talk with your doctor. You should also talk with them if you’re breastfeeding or considering breastfeeding. Your doctor can recommend treatment options other than Femara.

Both Femara and anastrozole (Arimidex) are used to treat certain types of breast cancer in females* who have gone through menopause.

Both Femara and Arimidex belong to a group of drugs called aromatase inhibitors. The drugs work by lowering estrogen levels in your body, which helps stop breast cancer from growing.

If you’d like to know more about how Femara and Arimidex compare with each other, see this detailed breakdown. And let your doctor know if you have more questions about these medications.

* In this article, we use the term “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

Don’t take more Femara than your doctor prescribes. Using more than this can lead to serious side effects.

What to do in case you take too much Femara

Call your doctor if you think you’ve taken too much Femara. You can also call 800-222-1222 to reach the American Association of Poison Control Centers, or use its online resource. However, if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.

If you have questions about using Femara for breast cancer, talk with your doctor or pharmacist.

You may want to ask about other treatments for breast cancer. If so, this article on breast cancer treatment options may be helpful for you.

Here are a few other questions you may want to ask your doctor about Femara:

  • Should I use other breast cancer treatments while taking Femara?
  • Will my breast cancer come back after I stop Femara treatment?
  • Am I at a higher risk for certain side effects from Femara?

In addition, you can learn about breast cancer and its treatment options by subscribing to Healthline’s breast cancer newsletter.

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 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.