Generic Name: anastrozole (an AS troe zole)
Brand Names: Arimidex
Medically reviewed by Sanjai Sinha, MD Last updated on Apr 22, 2019.
What is Arimidex?
Arimidex (anastrozole) lowers estrogen levels in postmenopausal women, which may slow the growth of certain types of breast tumors that need estrogen to grow in the body.
Arimidex is used to treat breast cancer in postmenopausal women. It is often given to women whose cancer has progressed even after taking tamoxifen (Nolvadex, Soltamox).
Arimidex may also be used for purposes not listed in this medication guide.
Do not use Arimidex if you are pregnant. It could harm the unborn baby.
Arimidex may not work as well if you take it together with estrogen medication (such as hormone replacement therapy, estrogen creams, or birth control pills, injections, implants, skin patches, and vaginal rings).
Arimidex may increase your risk of a stroke or blood clot. Call your doctor at once if you have sudden numbness or weakness, (especially on one side of the body), sudden severe headache, slurred speech, or problems with vision or balance.
Before taking this medicine
You should not use Arimidex if you are allergic to anastrozole, if you are breast-feeding a baby, or if you have not yet completed menopause. Arimidex is not for use in men or children.
To make sure Arimidex is safe for you, tell your doctor if you have:
a history of stroke or blood clot;
severe liver disease;
high cholesterol; or
osteoporosis or low bone mineral density.
Arimidex can decrease bone mineral density, which may increase your risk of developing osteoporosis. Your bone mineral density may need to be tested before and during treatment with anastrozole.
Although it is not likely that a postmenopausal woman would be pregnant, anastrozole could harm an unborn baby. Do not take this medicine if you are pregnant or may become pregnant. Use effective birth control if you are not past menopause, and tell your doctor right away if you become pregnant during treatment.
It is not known whether anastrozole passes into breast milk or if it could harm a nursing baby. You should not breast-feed while you are using Arimidex.
You may need to take a pregnancy test before using Arimidex, to make sure you are not pregnant.
How should I take Arimidex?
Arimidex is usually taken once per day. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.
You may take Arimidex with or without food.
You may need to keep taking this medication for up to 5 years. Follow your doctor's instructions.
Store at room temperature away from moisture and heat.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
What should I avoid?
Anastrozole can pass into body fluids (urine, feces, vomit). Caregivers should wear rubber gloves while cleaning up a patient's body fluids, handling contaminated trash or laundry or changing diapers. Wash hands before and after removing gloves. Wash soiled clothing and linens separately from other laundry.
This medication may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.
Arimidex side effects
Get emergency medical help if you have any signs of an allergic reaction to Arimidex: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
shortness of breath (even with mild exertion), swelling, rapid weight gain;
a bone fracture;
liver problems - nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
signs of a stroke - sudden numbness or weakness (especially on one side of the body), sudden severe headache, slurred speech, problems with vision or balance; or
severe skin reaction - fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.
Common Arimidex side effects may include:
weakness, hot flashes;
numbness or tingly feeling in your skin;
swelling in your ankles or feet;
joint pain or stiffness, problems with your fingers while gripping;
sore throat, headache, back pain, bone pain;
depression, mood changes, sleep problems (insomnia);
high blood pressure (severe headache, blurred vision, pounding in your neck or ears);
nausea, vomiting; or
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What other drugs will affect Arimidex?
Arimidex may not work as well if you take it together with an estrogen medication (such as hormone replacement therapy, estrogen creams, or birth control pills, injections, implants, skin patches, and vaginal rings). Before you start taking Arimidex, tell your doctor if you also take tamoxifen or estrogen.
Other drugs may interact with Arimidex, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Arimidex only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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- Drug class: aromatase inhibitors