Generic name: anastrozole [ an-AS-troe-zole ]
Brand name: Arimidex
Drug classes: Aromatase inhibitors, Hormones / antineoplastics

Medically reviewed by Drugs.com. Last updated on Aug 10, 2023.

Uses for anastrozole

Anastrozole is used to treat early hormone receptor-positive breast cancer. It is also used for first-line treatment of hormone receptor-positive or hormone receptor-unknown advanced or metastatic (cancer that has spread) breast cancer. Anastrozole is also used to treat advanced breast cancer that has grown or spread after tamoxifen treatment. This medicine is used only in women who have already stopped menstruating (postmenopausal).

Many breast cancer tumors grow in response to estrogen. This medicine interferes with the production of estrogen in the body. As a result, the amount of estrogen that the tumor is exposed to is reduced, limiting the growth of the tumor.

This medicine is available only with your doctor's prescription.

Before using anastrozole

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of anastrozole in children. However, efficacy has not been established to treat teenage boys with pubertal gynecomastia and to treat precocious puberty in teenage girls with McCune-Albright Syndrome.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of anastrozole in the elderly.

Breast Feeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with Medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Bone problems (eg, osteoporosis) or
• Hypercholesterolemia (high cholesterol or fat in the blood) or
• Ischemic heart disease (eg, heart attack, angina), history of, or
• Liver disease—Use with caution. May make these conditions worse.

• Premenopausal women (still having menstrual cycles)—Should not be used in these patients.

Proper use of anastrozole

Take this medicine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. To do so may increase the chance for side effects.

This medicine comes with a patient information leaflet. Read and follow these instructions carefully. Ask your doctor if you have any questions.

You may take this medicine with or without food.

Anastrozole sometimes causes nausea, vomiting, or diarrhea. However, it is very important that you continue to use the medicine, even if you begin to feel ill. Ask your doctor for ways to prevent these effects or make them less severe.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage form (tablets):
  • For breast cancer:
    • Adults—1 milligram (mg) once a day.
    • Children—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions while using anastrozole

It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

It is unlikely that a postmenopausal woman may become pregnant. But, you should know that using this medicine while you are pregnant could harm your unborn baby. Use an effective form of birth control during treatment with this medicine and for at least 3 weeks after the last dose. If you think you have become pregnant while using this medicine, tell your doctor right away.

Do not use this medicine together with tamoxifen (Nolvadex®, Soltamox®).

This medicine may cause serious allergic reactions, including anaphylaxis and angioedema, which can be life-threatening and require immediate medical attention. Call your doctor right away if you have itching, hives, hoarseness, trouble breathing or swallowing, or any swelling of your hands, face, or mouth while you are using this medicine.

Check with your doctor right away if you start having chest pains or difficulty with breathing. This medicine may increase the chance of heart problems, including heart attack, in women who have a history of ischemic heart disease.

This medicine may decrease bone mineral density when used for a long time. A low bone mineral density can cause weak bones or osteoporosis. If you have any questions about this, talk to your doctor.

This medicine may increase your cholesterol or fat in the blood. If this happens, your doctor may give you medicine to lower the cholesterol and fat.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems, and herbal or vitamin supplements.

Side Effects of anastrozole

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

• Blurred vision
• bone pain
• chest pain or discomfort
• dizziness
• headache
• nervousness
• pounding in the ears
• slow or fast heartbeat
• swelling of the feet or lower legs

Less common

• Arm, back, or jaw pain
• chest tightness or heaviness
• chills
• cough
• cough producing mucus
• difficult or painful urination
• difficulty breathing
• dizziness, severe
• fever
• headache, continuing
• hoarseness
• increased blood pressure
• lower back or side pain
• nausea
• pain, tenderness, bluish color, or swelling of the foot or leg
• sore throat
• sweating
• unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
• vaginal bleeding (unexpected and heavy)

Incidence not known

• Blistering, peeling, or loosening of the skin
• confusion
• constipation
• dark urine
• depression
• diarrhea
• difficulty swallowing
• dry mouth
• general tiredness and weakness
• hives or welts, itching, skin rash
• incoherent speech
• increased urination
• joint or muscle pain
• large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or genitals
• light-colored stools
• loss of appetite
• metallic taste
• muscle weakness
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• red skin lesions, often with a purple center
• red, irritated eyes
• sores, ulcers, or white spots in the mouth or on the lips
• stomach pain
• thirst
• upper right abdominal pain
• vomiting
• weight loss
• yellow eyes and skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

• Back pain
• belching
• body aches or pain
• congestion
• decrease in height
• feeling of warmth
• flushing or redness of the skin, especially on the face and neck
• heartburn
• increased appetite
• indigestion
• lack or loss of strength
• mood or mental changes
• pain in the back, ribs, arms, or legs
• pain, general
• pelvic pain
• runny nose
• stomach discomfort or upset
• tender, swollen glands in the neck
• trouble in swallowing
• voice changes

Less common

• Anxiety
• breast pain
• dryness of the vagina
• general feeling of discomfort or illness
• joint stiffness
• loss of hair
• numbness or tingling of the hands or feet
• shivering
• sleepiness
• trouble sleeping
• weight gain

Incidence not known

• Difficulty in moving
• muscle cramps or stiffness
• swollen joints

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Commonly used brand name(s)

In the U.S.

• Arimidex

Available Dosage Forms:

• Tablet

Therapeutic Class: Antineoplastic Agent

Pharmacologic Class: Aromatase Inhibitor

Frequently asked questions

• What is Veridex used for?
• What happens when you stop taking Arimidex?
• Does anastrozole cause weight gain?
• How soon do the side effects of Arimidex start?
• Does anastrozole cause hair loss?
• How long do side effects last after stopping Arimidex?
• What does anastrozole do to your body?
• How do I take anastrozole on a cycle and how much?
• How much does Arimidex increase survival?

View more FAQ

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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