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.

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.

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.

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.