Skip to Content
Looking to save on your medications?  Find out how 

Anastrozole

Brand names: Arimidex

What is anastrozole used for?

  • Anastrozole is used to treat breast cancer in women after menopause (change of life).
  • Anastrozole may be given to you for other reasons. Talk to your doctor.

Before taking anastrozole, tell your doctor:

  • If you are allergic to anastrozole; any part of this medicine; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
  • If you are taking any of these drugs: Estrogen products or tamoxifen.
  • If you have not been through menopause or you are still able to have a baby.
  • If you are breast-feeding. Do not breast-feed while you take anastrozole and for 2 weeks after your last dose.

This is not a list of all drugs or health problems that interact with anastrozole.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take anastrozole with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take anastrozole?

  • Tell all of your health care providers that you take anastrozole. This includes your doctors, nurses, pharmacists, and dentists.
  • Have blood work checked as you have been told by the doctor. Talk with the doctor.
  • This medicine lowers the estrogen in your body, which may cause your bones to get thinner and weaker. This may raise the chance of broken bones like in the spine, hip, and wrist. Talk with your doctor.
  • Have a bone density test as you have been told by your doctor. Talk with your doctor.
  • High cholesterol has happened with anastrozole. If you have questions, talk with the doctor.
  • This medicine may cause fertility problems. This may affect being able to have children. Talk with the doctor.
  • This medicine may cause harm to an unborn baby. A pregnancy test will be done before you start anastrozole to show that you are NOT pregnant.
  • Women must use birth control while taking anastrozole and for some time after the last dose. Ask your doctor how long to use birth control. If you get pregnant, call your doctor right away.

How is anastrozole best taken?

Use anastrozole as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • Take with or without food.
  • Keep taking anastrozole as you have been told by your doctor or other health care provider, even if you feel well.

What do I do if I miss a dose?

  • Take a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.

What are the side effects of anastrozole that I need to call my doctor about immediately?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
  • Signs of high blood pressure like very bad headache or dizziness, passing out, or change in eyesight.
  • Signs of a urinary tract infection (UTI) like blood in the urine, burning or pain when passing urine, feeling the need to pass urine often or right away, fever, lower stomach pain, or pelvic pain.
  • A burning, numbness, or tingling feeling that is not normal.
  • Swollen gland.
  • Bone pain.
  • Shortness of breath.
  • Swelling in the arms or legs.
  • Depression or other mood changes.
  • Change in eyesight.
  • Breast pain.
  • Vaginal bleeding that is not normal.
  • Vaginal itching or discharge.
  • People who have ever had a block in their heart blood vessels (ischemic heart disease) may have more signs of problems with blood flow to the heart. Call your doctor right away if you have new or worse chest pain or shortness of breath.

What are some other side effects of anastrozole?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Hot flashes.
  • Feeling dizzy, tired, or weak.
  • Headache.
  • Upset stomach or throwing up.
  • Joint pain or swelling.
  • Muscle pain.
  • Trouble sleeping.
  • Cough.
  • Sore throat.
  • Back pain.
  • Diarrhea or constipation.
  • Weight gain.
  • Anxiety.
  • Sweating a lot.
  • Flu-like signs.
  • Dry mouth.
  • Pelvic pain.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

If overdose is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Anastrozole Images

How do I store and/or throw out anastrozole?

  • Store at room temperature in a dry place. Do not store in a bathroom.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

Consumer information use and disclaimer

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else's drugs.
  • Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about anastrozole, please talk with your doctor, nurse, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

This information should not be used to decide whether or not to take anastrozole or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to anastrozole. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.

Source: Wolters Kluwer Health. Last updated April 5, 2023.