What Is Anastrozole and How Does It Work?

Anastrozole is a non-steroidal aromatase inhibitor used to treat breast cancer in postmenopausal women. Anastrozole is often given to women whose cancer has progressed even after taking tamoxifen (Nolvadex, Soltamox).

  • Anastrozole is available under the following different brand names: Arimidex.

What Are Dosages of Anastrozole?

Dosages of Anastrozole:

Dosage Forms and Strengths


  • 1 mg

Dosage Considerations – Should be Given as Follows:

Breast Cancer

Postmenopausal women


  • 1 mg orally once daily; continue until tumor progression


  • Adjuvant treatment: 1 mg orally once daily; optimal duration unknown; 5 years in the clinical trial


  • It May be taken with or without food

Hepatic Impairment

  • Mild-to-moderate impairment or stable hepatic cirrhosis: Dose adjustment not necessary
  • Severe hepatic impairment: Not studied

Pediatric: Use not recommended

What Are Side Effects Associated with Using Anastrozole?

Side effects of anastrozole include:

  • Hot flashes
  • Vasodilation
  • Fatigue
  • Mood disturbances
  • Nausea and vomiting
  • Weakness
  • Arthritis
  • Pain
  • Joint pain or stiffness
  • Scratchy or sore throat
  • Depression
  • High blood pressure (hypertension)
  • Bone pain
  • Increased cough
  • Osteoporosis
  • Rash
  • Upset stomach
  • Loss of appetite
  • Body aches and pains
  • Breast swelling/tenderness/pain
  • Tiredness
  • Hair thinning
  • Mood changes
  • Problems with your fingers while gripping
  • Numbness, tingling, cold feeling, or weakness in your hand or wrist

Less common side effects of anastrozole include:

Postmarketing side effects of anastrozole reported include:

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

What Other Drugs Interact with Anastrozole?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Severe Interactions of anastrozole include:
    • None
  • Serious Interactions of anastrozole include:
    • bazedoxifene/conjugated estrogens
    • conjugated estrogens
    • estradiol
    • estrogens conjugated synthetic
    • estrogens esterified
    • estropipate
    • ethinylestradiol
    • tamoxifen
  • Moderate Interactions of anastrozole include:
  • Mild Interactions of anastrozole include:
    • ruxolitinib

This information does not contain all possible interactions or adverse effects. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns, or for more information about this medicine.

What Are Warnings and Precautions for Anastrozole?


  • This medication contains anastrozole. Do not take Arimidex if you are allergic to anastrozole or any ingredients contained in this drug.
  • Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately


  • Hypersensitivity
  • May cause fetal harm or loss; use is contraindicated in women who are or may become pregnant

Effects of Drug Abuse

  • No information available

Short-Term Effects

  • See "What Are Side Effects Associated with Using Anastrozole?"

Long-Term Effects

  • Decreases lumbar spine and total hipbone mineral density; increased risk of fractures and osteoporosis
  • See "What Are Side Effects Associated with Using Anastrozole?"


  • Increased incidence of ischemic cardiovascular events in women with preexisting ischemic heart disease; use only if benefits greatly outweigh risks
  • Decreases lumbar spine and total hipbone mineral density; increased risk of fractures and osteoporosis
  • Elevated serum cholesterol reported; monitor closely
  • Affords no clinical benefit to premenopausal women with breast cancer
  • Increased risk of ischemic cardiovascular events in patients with pre-existing ischemic cardiac disease

Pregnancy and Lactation

  • Do not use anastrozole in pregnancy. The risks involved outweigh the potential benefits. Safer alternatives exist
  • It is unknown whether anastrozole is excreted in the milk; it is not recommended given the potential for serious adverse reactions in nursing infants
Medscape. Anastrozole.

RxList. Arimidex Side Effects Center.

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