The short answer
Arimidex (Anastrozole) is a hormone therapy for breast cancer. It blocks the aromatase enzyme so the body makes less estrogen, which can slow the growth of estrogen-fueled breast cancers after menopause. It is used to help treat hormone-receptor-positive breast cancer in postmenopausal women, and is usually given as one pill taken by mouth each day. Like all cancer medicines it can cause side effects; this page explains the common ones and the warning signs to report. It is educational only and not a substitute for your care team's advice.
Arimidex is the brand name; its generic name is anastrozole.
It is a hormone therapy for breast cancer — it blocks the aromatase enzyme so the body makes less estrogen, which can slow the growth of estrogen-fueled breast cancers after menopause.
It is used to help treat hormone-receptor-positive breast cancer in postmenopausal women.
It is usually given as one pill taken by mouth each day.
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The full explanation.
What it is
Arimidex (Anastrozole) is a cancer medicine. It is a type of hormone therapy called an aromatase inhibitor. In plain terms, it blocks the aromatase enzyme so the body makes less estrogen, which can slow the growth of estrogen-fueled breast cancers after menopause. You may see it called by its brand name, Arimidex, or by its generic name, anastrozole. This page is a general explainer based on the National Cancer Institute's drug information; it does not replace the specific instructions your own care team gives you.
What cancers it treats
According to the National Cancer Institute, anastrozole is approved to help treat hormone-receptor-positive breast cancer in postmenopausal women. Whether it is the right choice for a particular person depends on the cancer type, its stage, test results such as biomarkers, and other treatments already tried. Your oncology team can explain why it was chosen for your situation.
How it's given
As one pill taken by mouth each day. It is taken by mouth once a day, often for several years. Take it as prescribed and talk with your team before stopping. How much, how often, and for how long vary from person to person, so follow the exact schedule your care team gives you. If you miss an appointment or a dose, ask your team what to do rather than changing anything yourself.
Common side effects
Not everyone gets the same side effects, and some people have only mild ones. With anastrozole, commonly reported effects include hot flashes, joint or muscle aches, tiredness, bone thinning over time, and mood changes. Many of these can be eased with supportive care. Tell your care team if you notice anything new, if a side effect is getting worse, or if it is making everyday life hard — they can often help, and knowing early usually makes problems easier to manage. Side effects do not tell you whether the medicine is working.
Serious warning signs
Some problems need prompt attention. Contact your care team right away (or use the emergency number they give you) if you notice chest pain or sudden shortness of breath, pain or swelling in one leg, sudden weakness on one side of the body or trouble speaking, and a rash or swelling that could be an allergic reaction. This is not a complete list, and it cannot tell you whether your own situation is an emergency — that is exactly why your team gives you personal instructions and a number to call. When in doubt, it is always reasonable to check in with them.
The bottom line
Arimidex (Anastrozole) is one of many tools used in cancer care. Understanding what it is, how it is given, and what to watch for can make treatment feel less overwhelming and help you speak up early about side effects. Keep a simple list of anything you notice, bring your questions to appointments, and remember that your care team — not a website — is the right source for decisions about your treatment.
Words to know
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Common questions
▸What is Arimidex?
Arimidex (Anastrozole) is a hormone therapy for breast cancer. It blocks the aromatase enzyme so the body makes less estrogen, which can slow the growth of estrogen-fueled breast cancers after menopause. It is used to help treat hormone-receptor-positive breast cancer in postmenopausal women.
▸How is Arimidex given?
It is usually given as one pill taken by mouth each day. It is taken by mouth once a day, often for several years. Take it as prescribed and talk with your team before stopping. The exact schedule is set by your care team.
▸What are the common side effects of Arimidex?
Commonly reported side effects include hot flashes, joint or muscle aches, tiredness, bone thinning over time, and mood changes. Not everyone gets them, and many can be managed. Tell your care team about anything new or worsening.
▸Does Arimidex cure cancer?
That depends on the person, the cancer type, and its stage. For some people a medicine like this can control cancer for a long time or be part of a curative plan; for others the goal is to slow the cancer or ease symptoms. Your care team can explain the goal in your situation.
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