Uses

What is anastrozole used for?

Anastrozole is commonly used to treat certain types of breast cancer, including hormone receptor- positive breast cancer, in women after menopause.

Anastrozole may also be used for other conditions as determined by your healthcare provider.

How does anastrozole work (mechanism of action)?

Anastrozole belongs to a class of medicines called aromatase inhibitors. It works by blocking an enzyme called aromatase that helps produce estrogen in the body. By lowering the amount of estrogen, anastrozole can help prevent the growth of tumors that rely on estrogen to grow.

How is anastrozole supplied (dosage forms)?

Anastrozole is available as Arimidex and generic anastrozole as 1 mg oral tablets that are taken by mouth.

How should I store anastrozole?

Anastrozole should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place, in a tight container.

Side Effects

What are the most common side effects of anastrozole?

The most common side effects of anastrozole are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Hot flashes
  • Feeling unusually weak or tired
  • Pain, including back pain, bone pain, headache,  joint pain, or sore throat
  • Nausea and vomiting
  • Rash
  • Weak bones (see below)
  • Trouble sleeping
  • Fluid retention
  • Cough or shortness of breath
  • High blood pressure
  • Depression

There may be other side effects of anastrozole that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of anastrozole?

While less common, the most serious side effects of anastrozole are described below, along with what to do if they happen.

Severe Allergic Reactions. Anastrozole may cause allergic reactions, which can be serious. Stop taking anastrozole and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Skin Reactions. Anastrozole can cause a skin reaction. Stop taking anastrozole and call your healthcare provider right away if you develop any skin lesion, such as blisters or ulcers.

Weak Bones. Taking anastrozole for a long time may cause your bones to become weaker, leading to reduced bone density (osteopenia). It may also cause a more serious condition called osteoporosis, which can cause bones to break (fracture) more easily. If you take anastrozole, your healthcare provider may monitor your bone density. Tell your healthcare provider if you break a bone, and get a bone mineral density test if one is ordered for you.

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking anastrozole. Stop taking anastrozole and call your healthcare provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine (pee)
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

High Cholesterol. Taking anastrozole may cause levels of cholesterol (fat) in your blood to go up. If you take anastrozole, your healthcare provider may monitor your cholesterol levels. Keep all appointments to have your blood cholesterol checked.

Warnings & Precautions

Who should not use anastrozole?

Allergies to Ingredients. People who are allergic to any of the following should not take anastrozole.

  • Anastrozole
  • Arimidex
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific anastrozole products they stock.

What should I know about anastrozole before using it?

Do not take anastrozole unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share anastrozole with other people, even if they have the same condition as you. It may harm them.

Keep anastrozole out of the reach of children.

Anastrozole may be associated with carpal tunnel syndrome, which is caused by pressure on a nerve in your wrist. Tell your healthcare provider right away if you have numbness, tickling, or tingling in your hand or fingers.

Ask your healthcare provider about your vitamin D level. You may need to take a supplement.

What should I tell my healthcare provider before using anastrozole?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if anastrozole is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • High cholesterol
  • Liver problems
  • Osteopenia or osteoporosis
  • Menstrual periods (if you are not past menopause)

Heart Disease. Anastrozole may cause an increase in symptoms of poor blood flow to the heart in people who have coronary artery disease. Get emergency help right away if you get new or worsening chest pain or trouble breathing when taking this medicine.

Other Medicines and Supplements. Anastrozole may interact with other medicines and supplements. Before taking anastrozole, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. Anastrozole may cause harm to an unborn baby. A negative pregnancy test is necessary before starting treatment. If you can become pregnant, use effective birth control while you are taking anastrozole and for 3 weeks after your last dose. Talk to your healthcare provider about your birth control options. If you become pregnant or think you may be pregnant, tell your healthcare provider right away.

Breastfeeding. Do not breastfeed during treatment with anastrozole or for 2 weeks after your last dose. It is not known if anastrozole passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed.

Interactions

Does anastrozole interact with foods or drinks?

There are no known interactions between anastrozole and foods or drinks.

There are no known interactions between anastrozole and alcohol.

Does anastrozole interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking anastrozole.

  • Tamoxifen, a medicine that is used to treat and prevent breast cancer
  • An estrogen medicine, such as hormone replacement, certain birth control pills, or estrogen creams, rings, or suppositories

This may not be a complete list of medicines that can interact with anastrozole. Always check with your healthcare provider.

Does Anastrozole (Arimidex) interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much anastrozole?

If you or someone else has used too much anastrozole, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of anastrozole?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.

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