Anastrozole (Arimidex®)

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About This Drug

Anastrozole is used to treat cancer. This drug is given orally (by mouth.)

Possible Side Effects

  • Hot flashes or sudden skin flushing may happen. You may also feel warm or red.
  • Weakness
  • Pain in the joints, arthritis
  • Fractures 
  • Back pain
  • Pain
  • Headache
  • Trouble sleeping
  • Depression
  • Headache
  • Swelling of your legs, ankles and/or feet 
  • Lymphedema - swelling in your affected arm 
  • High blood pressure. Your doctor will check your blood pressure as needed.
  • Rash 
  • Nausea and vomiting (throwing up)
  • Sore throat
  • Cough, trouble breathing
  • Osteoporosis -your bones may become weak and brittle.

Note: Each of the side effects above was reported in 10% or greater of patients treated with anastrozole. Not all possible side effects are included above.

Warnings and Precautions

  • If you have a history of severe heart disease, this drug may increase your risk of a heart attack. 
  • Decrease in your bone mass, which may put you at risk of bone fractures. Your doctor may monitor your bone mineral density.
  • Your total cholesterol level may increase; your doctor may monitor your cholesterol level.  
  • Allergic reactions, including anaphylaxis are rare but may happen in some patients. Signs of allergic reaction to this drug may be swelling of the face, feeling like your tongue or throat are swelling, trouble breathing, rash, itching, fever, chills, feeling dizzy, and/or feeling that your heart is beating in a fast or not normal way. If this happens, do not take another dose of this drug. You should get urgent medical treatment.

How to Take Your Medication

  • Swallow the medicine with or without food. 
  • Missed dose: If you miss a dose, take it as soon as you think about it.  If it is close to your next dose, then skip the missed dose and go back to your normal schedule.  Do not take 2 doses at the same time or extra doses.
  • Handling: Wash your hands after handling your medicine; your caretakers should not handle your medicine with bare hands and should wear latex gloves.
  • Storage: Store this medicine in the original container at room temperature. Discuss with your nurse or your doctor how to dispose of unused medicine.

    Treating Side Effects

    • Drink plenty of fluids (a minimum of eight glasses per day is recommended).
    • If you throw up or have loose bowel movements, you should drink more fluids so that you do not become dehydrated (lack water in the body from losing too much fluid). 
    • To help with nausea and vomiting, eat small, frequent meals instead of three large meals a day. Choose foods and drinks that are at room temperature. Ask your nurse or doctor about other helpful tips and medicine that is available to help or stop lessen these symptoms.
    • Keeping your pain under control is important to your well-being. Please tell your doctor or nurse if you are experiencing pain. 
    • If you are having trouble sleeping, talk to your nurse or doctor on tips to help you sleep better.
    • If you are feeling depressed, talk to your nurse or doctor about it.
    • If you get a rash do not put anything on it unless your doctor or nurse says you may. Keep the area around the rash clean and dry. Ask your doctor for medicine if your rash bothers you.

    Food and Drug Interactions

    • There are no known interactions of anastrozole with food. 
    • Check with your doctor or pharmacist about all other prescription medicines and dietary supplements you are taking before starting this medicine as there are a lot of known drug interactions with anastrozole. Also, check with your doctor or pharmacist before starting any new prescription or over-the-counter medicines, or dietary supplement to make sure that there are no interactions.
    • Avoid the use of estrogen containing products while taking anastrozole as this may lower the levels of the drug in your body, which can make it less effective.

    When to Call the Doctor

    Call your doctor or nurse if you have any of these symptoms and/or any new or unusual symptoms:

    • Fever of 100.5 F (38 C) or higher 
    • Chills
    • Pain that does not go away, or is not relieved by prescribed medicines
    • Headache that does not go away
    • Blurry vision or other changes in eyesight
    • You cough up yellow, green, or bloody mucus
    • Wheezing or trouble breathing 
    • Extreme weakness that interferes with normal activities
    • Fatigue that interferes with your daily activities
    • Lose interest in your daily activities that you used to enjoy and feeling this way every day, and/or you feel hopelessness.
    • Nausea that stops you from eating or drinking  and/or is not relieved by prescribed medicines
    • Throwing up more than 3 times a day 
    • Weight gain of 5 pounds in one week (fluid retention) 
    • New rash and/or itching
    • Rash that is not relieved by prescribed medicines
    • Signs of allergic reaction: swelling of the face, feeling like your tongue or throat are swelling, trouble breathing, rash, itching, fever, chills, feeling dizzy, and/or feeling that your heart is beating in a fast or not normal way
    • Tickling, tingling or numbness 
    • If you think you are pregnant

    Reproduction Concerns

    • Pregnancy warning: This drug may have harmful effects on the unborn baby. This drug is not indicated for women who could become pregnant or are pregnant. Let your doctor know right away if you think you may be pregnant.
    • Breastfeeding warning: It is not known if this drug passes into breast milk.  For this reason, women should talk to their doctor about the risks and benefits of breast feeding during treatment with this drug because this drug may enter the breast milk and cause harm to a breast feeding baby.
    • Fertility warning: Human fertility studies have not been done with this drug. Talk with your doctor or nurse if you plan to have children.  

    Revised September 2017