Anastrozole: What It Is, How It Works, and What to Expect

Here’s something many people don’t know: anastrozole (brand name Arimidex) can cut estrogen levels dramatically, and that change is exactly why it helps certain breast cancers—but it’s also why side effects can hit fast. If you or someone you care about is starting anastrozole, this plain guide tells you what the drug does, common side effects, simple safety tips, and smart questions to ask your doctor.

Anastrozole is an aromatase inhibitor. In postmenopausal people with estrogen-receptor positive (ER+) breast cancer, it blocks the enzyme aromatase, which turns androgens into estrogen. Lowering estrogen helps slow or stop the growth of tumors that rely on that hormone. Doctors often use it after surgery, or instead of tamoxifen for some patients.

Common dosing and what to expect

Typical dosing is one 1 mg tablet once a day, taken at the same time each day, with or without food. Missing one dose occasionally is usually not a crisis, but don’t double up the next day—talk to your care team if you miss several doses. Many people take anastrozole for five years, though your doctor may recommend a different length based on your situation.

Side effects and simple ways to manage them

Lowering estrogen causes the most common side effects. Think hot flashes, joint and bone pain, stiffness, and vaginal dryness. Bone thinning is a real concern—ask about a baseline bone density scan (DEXA) before starting. Calcium, vitamin D, weight-bearing exercise, and sometimes a bone-strengthening medicine can help protect bones.

For joint pain, gentle stretching, low-impact exercise, and over-the-counter pain relievers often help. Vaginal dryness can be eased with water-based lubricants or local treatments your doctor recommends. If hot flashes are severe, there are non-hormonal medications and lifestyle tips that can reduce them—ask your team for options that won’t interfere with cancer care.

Watch for warning signs: new or worsening shortness of breath, chest pain, or severe leg swelling—report those immediately. Also tell your doctor about new mood changes or significant memory problems.

Drug interactions matter. Some medications, supplements, or herbal products can affect how anastrozole works. Always run new prescriptions, over-the-counter meds, and herbs by your pharmacist or oncologist.

Practical tips: store tablets at room temperature away from moisture, use a pillbox or phone reminder, and bring a current medication list to every visit. Keep a simple symptom log—note joint pain, sleep changes, or hot flashes and how they affect daily activities. That makes follow-up visits more useful.

Finally, don’t be shy about asking your care team for help. Ask why anastrozole was chosen, how long you’ll take it, how they’ll monitor bone health, and which side effects should prompt a call. Small questions now save worries later, and your team wants you to feel informed and supported while on treatment.