Arimidex (anastrozole) is a prescription brand-name medication. It’s approved by the Food and Drug Administration (FDA) to treat the following types of breast cancer in females* who have gone through menopause:
- early hormone receptor-positive (HR+) breast cancer
- locally advanced or metastatic breast cancer that’s HR+ or the HR status is not known
- locally advanced or metastatic breast cancer that has spread or returned after treatment with a drug called tamoxifen
Here are some fast facts on Arimidex:
- Active ingredient: anastrozole
- Drug class: aromatase inhibitor
- Drug form: oraltablets
As with other medications, Arimidex can cause side effects. Read on to learn about potential common, mild, and serious side effects. For a general overview of Arimidex, including details about its uses, see this article.
* Sex and gender exist on spectrums. Use of the term “female” in this article refers to sex assigned at birth.
Arimidex 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. But 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 Arimidex in clinical studies. These side effects can vary depending on which condition the drug is being used to treat.
More common side effects in people taking Arimidex for early breast cancer include:
- hot flashes
- weakness
- arthritis
- general pain
- joint pain
More common side effects in people taking Arimidex for locally advanced or metastatic breast cancer include:
- hot flashes
- nausea
- weakness
- general pain
- headache*
*For more information on this side effect, see “Side effect specifics” below.
Mild side effects can occur with Arimidex use. But they didn’t vary significantly among the types of breast cancer the drug is used to treat. This list doesn’t include all possible mild side effects of Arimidex. For more information, you can refer to the medication’s prescribing information.
Mild side effects that have been reported with Arimidex include:
- headache*
- pain, which may affect your joints, back, or bones*
- hot flashes
- weakness
- arthritis
- nausea and vomiting
- fatigue
- rash
- insomnia
- peripheral edema (a type of swelling and fluid buildup) in your ankles, feet, or lower legs
- sore throat
- dizziness
- carpal tunnel syndrome (squeezed nerve in the wrist)
- lymphedema (a type of swelling and fluid buildup) in your arm
- cough
- shortness of breath
These side effects may be temporary, lasting a few days to weeks. But 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 side effects of the medication. If you develop a side effect while taking Arimidex and want to tell the FDA about it, visit MedWatch.
*For more information on this side effect, see “Side effect specifics” below.
Arimidex may cause serious side effects. But they didn’t vary based on which type of breast cancer the drug is being used to treat. The list below may not include all possible serious side effects of Arimidex. For more information, you can refer to the medication’s prescribing information.
If you develop serious side effects while taking Arimidex, 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:
- Decreased bone density (weakened bones), which usually doesn’t cause symptoms.
- Skin reactions. Symptoms can include:
- blisters
- lesions (skin changes such as patches or bumps)
- ulcers (sores)
- Increased cholesterol levels, which usually don’t cause symptoms and are often discovered in a blood test.
- Heart-related side effects.*
- Allergic reaction.*
*For more information on this side effect, see “Side effect specifics” below.
Long-term side effects
Most Arimidex side effects are temporary, lasting a few days to weeks.
However, in rare cases, Arimidex can cause some side effects that are long term. For example, decreased bone density and carpal tunnel syndrome can be long-term problems that require treatment. Other long-term side effects that are described below in “Side effect specifics” include heart-related side effects and liver problems.
If your side effects last longer than a few days to weeks, bother you, or become severe, talk with your doctor or pharmacist.
Arimidex 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 Arimidex after 5 years?
If you have been taking Arimidex for 5 years, you may have fewer mild side effects than someone who recently started treatment. This is because some mild side effects last a short time.
Serious side effects of Arimidex are expected to be the same however long you take the drug for. Certain side effects, such as decreased bone density, may last a long time. To learn more, see “Long-term side effects” above.
For more information about side effects of Arimidex, talk with your doctor.
How do Arimidex’s side effects differ between males and females?
Arimidex is not approved for use in males.* The drug hasn’t been studied in this group of people.
To learn about side effects that Arimidex may cause in females,* you can refer to the rest of this article. You can also talk with your doctor or pharmacist.
* Sex and gender exist on spectrums. Use of the terms “male” and “female” in this article refers to sex assigned at birth.
Is hair loss a side effect Arimidex?
Hair loss wasn’t reported as a side effect of Arimidex in clinical studies. But in very rare cases, a few people taking the medication reported hair thinning.
If you’re concerned about hair loss or thinning while taking Arimidex, talk with your doctor or pharmacist. They may be able to recommend a treatment. Or your doctor may suggest a medication other than Arimidex.
Can Arimidex cause any permanent damage?
Most Arimidex side effects are temporary, lasting a few days to weeks. But in rare cases, Arimidex can cause some side effects that are long term. To learn more, see “Long-term side effects” in the “Serious side effects of Arimidex” section above. You can also speak with your doctor or pharmacist.
Should I expect liver problems, such as liver toxicity, with Arimidex?
Liver problems weren’t reported in clinical studies of Arimidex. But rare cases have been reported since the medication was approved. Because these cases happened outside of the studies, it’s not known for certain if Arimidex another factor caused the liver problems. Other factors could include a different medication.
The majority of people who reported liver problems with Arimidex didn’t experience any symptoms. In most cases, the only change noted is a slight increase in liver enzymes. However, in very rare instances, more severe problems such as hepatitis can occur.
Symptoms of severe liver problems can include:
- nausea and vomiting
- a general feeling of being unwell
- pain in the upper right abdomen
- jaundice (yellowing of your skin and the whites of your eyes)
Liver toxicity refers to injury to your liver due to a medication. A breast cancer drug called Soltamox (tamoxifen), which is similar to Arimidex, has been known to cause liver toxicity in
If you develop symptoms of liver problems while taking Arimidex, talk with your doctor. They’ll likely have you stop taking the medication and suggest other treatments for your condition.
Learn more about some of the side effects that Arimidex may cause.
Heart-related side effects
Arimidex can cause new or worsening heart-related side effects. These include heart attack, angina (chest pain or tightness), and cardiovascular problems caused by lack of blood flow to the heart. (The term “cardiovascular” refers to the heart and blood vessels.)
The side effects weren’t common in clinical studies of the drug. But they were most common in people who already had heart disease.*
Symptoms of heart-related side effects can include:
- pain, pressure, or aching in the chest
- nausea
- pain that reaches to the jaw, neck, back, or arms
- shortness of breath
Some
* For details, see the “Precautions for Arimidex” section below.
What you can do
If you have heart disease, be sure to talk with your doctor before you start taking Arimidex. They may decide that a different treatment is a better choice for you.
Headache
Headache is a possible side effect from Arimidex treatment. This was commonly reported in clinical studies of the drug.
What you can do
Talk with your doctor or pharmacist if you develop headaches while taking Arimidex. They may recommend a treatment such as an over-the-counter pain (OTC) reliever. This can include acetaminophen (Tylenol) and ibuprofen (Advil, Motrin). Keep in mind that you should not take any other medications, including OTC ones, with Arimidex unless you first speak with your doctor. They can check for any interactions with Arimidex.
Bone pain
It’s possible to have bone pain with Arimidex treatment. This was a common side effect reported in clinical studies.
What you can do
Talk with your doctor if you develop bone pain while taking Arimidex. They may recommend a treatment such as an OTC pain reliever. Examples include acetaminophen and ibuprofen. Keep in mind that you should not take any other medications, including OTC ones, with Arimidex unless you first speak with your doctor. They can check for any interactions with Arimidex.
If your bone pain won’t go away, your doctor will likely recommend trying a treatment other than Arimidex for your condition.
Allergic reaction
As with most drugs, Arimidex can cause an allergic reaction in some people. But this was very rare in clinical studies.
Symptoms can be mild or serious and can include:
- skin rash
- itching
- flushing
- swelling under your skin, typically in your lips, eyelids, feet, or hands
- 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 Arimidex. But if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.
Be sure to talk with your doctor about your health history before you take Arimidex. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. The conditions and factors to consider include:
High cholesterol. Taking Arimidex can increase your cholesterol levels. Your doctor will monitor your levels while you take Arimidex. If you already have high cholesterol, they may monitor you more closely. If you take medication for high cholesterol, your doctor may adjust the dosage if your cholesterol levels rise.
Ischemic heart disease. Before you take Arimidex, talk with your doctor about any heart problems you may have. If you have angina or have had a heart attack, your heart problems may worsen if you take Arimidex. Your doctor may recommend a different treatment for your condition.
Osteoporosis. Taking Arimidex can weaken your bones. This can worsen osteoporosis if you already have the condition. Worsened osteoporosis may increase your risk of broken bones. If you have osteoporosis, your doctor may prescribe a treatment to help protect your bones while you take Arimidex.
Severe liver problems. There have been a few reports of liver problems, such as hepatitis, since Arimidex was approved. If you have a liver problem, taking Arimidex may make it worse. Before you take the drug, talk with your doctor about any liver problems you may have. They may recommend a different treatment for your condition.
Allergic reaction. If you’ve had an allergic reaction to Arimidex or any of its ingredients, your doctor will likely not prescribe Arimidex. Talk with your doctor about which other treatments may be better choices for you.
Alcohol use with Arimidex
There’s no known direct interaction between drinking alcohol and taking Arimidex.
However, alcohol could worsen some side effects of Arimidex, including headache, nausea, and tiredness. The combination of alcohol and Arimidex may also increase your risk of osteoporosis.
Ask your doctor how much alcohol is safe for you to consume during your Arimidex treatment.
Pregnancy and breastfeeding while taking Arimidex
Here’s some information on pregnancy, breastfeeding, and Arimidex.
Pregnancy. Arimidex may harm a fetus if taken during pregnancy. This is based on how the drug works. Arimidex hasn’t been studied in pregnant people. If you can become pregnant, your doctor will order a pregnancy test before you start taking the medication.
You should use birth control while taking Arimidex and for 3 weeks or more after your last dose.
Breastfeeding. You should not breastfeed while taking Arimidex, and for at least 2 weeks after your last dose. The drug hasn’t been studied to see what effects it could have on milk production or a breastfed child. If you’re breastfeeding or considering it, talk with your doctor. They can advise you on healthy ways to feed your child and other treatment options.
Side effects can occur while taking Arimidex, but they’re usually mild. Most mild side effects of the drug go away with time and don’t require medical attention.
You should talk with your doctor right away if you become pregnant while taking Arimidex.
If you’d like to learn more about Arimidex, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug.
Besides talking with your doctor, you can do some research on your own. These articles might help:
- More information on Arimidex. For details on other aspects of Arimidex, refer to this article.
- Dosage details. For information on Arimidex’s dosage, see this article.
- A look at breast cancer. For details on breast cancer, visit our cancer hub and women’s health hub. You can also see our list of breast cancer articles.
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.