Anastrozole: What It Does, How to Use It Safely

Anastrozole is an aromatase inhibitor most commonly prescribed for postmenopausal women with hormone receptor–positive breast cancer. It lowers estrogen levels to slow or stop tumor growth. If you or someone you care for is starting Anastrozole, here's what matters most in plain language.

How Anastrozole works and who takes it

Anastrozole blocks the enzyme aromatase, which converts androgens into estrogen outside the ovaries. For women after menopause, those peripheral sources are the main estrogen producers, so blocking them reduces tumor fuel. Doctors use Anastrozole as adjuvant therapy after surgery, for metastatic disease, or to lower recurrence risk. It’s not typically used in premenopausal women unless ovarian suppression is also in place.

Men sometimes take Anastrozole off-label to lower estrogen caused by testosterone therapy or certain cancers. That use needs close medical supervision because men and women respond differently.

Common dosing, side effects, and monitoring

Standard dosing is 1 mg once daily by mouth. Take it at the same time every day with or without food. Don’t crush or chew tablets unless your pharmacist advises an alternative form.

Common side effects are joint pain, hot flashes, fatigue, and bone thinning. Many people notice achy joints after a few weeks or months; simple pain relievers, gentle exercise, and physical therapy help for many. Because Anastrozole can lower bone density, your doctor will likely order a DEXA scan and may recommend calcium, vitamin D, or a bone-protecting drug.

Less common but serious effects include high cholesterol, liver enzyme changes, and rare severe allergic reactions. If you develop sudden shortness of breath, chest pain, severe rash, or unexplained bruising, seek medical care right away.

Regular blood tests and clinic visits are normal while on Anastrozole. Tell your team about any new symptoms, mood changes, or unexplained weight shifts. If you miss a dose, take it as soon as you remember the same day; don’t double up the next day.

Drug interactions matter. Tell your doctor about prescription drugs, herbal supplements, and over-the-counter meds. Certain drugs can change how Anastrozole is processed and reduce its effectiveness or raise side effect risk.

If you plan pregnancy or are premenopausal, discuss options before starting treatment. Anastrozole can harm a fetus and is not a form of contraception. Fertility planning, egg preservation, or switching treatments may be necessary.

Want practical tips? Keep a symptom log so you and your doctor can spot patterns. Stay active with low-impact exercise for bones and joints. Ask about bone health checks and lipid panels. When in doubt, call your oncology nurse—they can often advise before a clinic visit is needed.

Buying medication: use licensed pharmacies, bring prescription, check for pharmacist contact, avoid suspiciously cheap sites, and keep meds in original packaging. If side effects interfere with daily life, ask about dose changes or switching to another class like tamoxifen.

Always talk openly with your care team—their experience matters more than internet advice. Keep questions written before appointments. Keep a medication card and carry it.