Anastrozole

What is Anastrozole?

Anastrozole is a prescription medicine used to treat certain breast cancers. It belongs to a drug class called aromatase inhibitors, a type of hormone (endocrine) therapy. It was first sold under the brand name Arimidex, and generic versions are widely available.

Approved uses: In the United States, anastrozole is approved for postmenopausal women with:

• Early breast cancer: Adjuvant treatment of hormone receptor-positive early breast cancer, given after surgery
• First-line treatment: Treatment of hormone receptor-positive or hormone receptor-unknown locally advanced or metastatic breast cancer
• Advanced breast cancer after tamoxifen: Treatment of advanced breast cancer that has grown after tamoxifen therapy

Formulation and strength: Anastrozole is taken by mouth as a 1 mg film-coated tablet. Other uses should be discussed only with your doctor.

What is the Recommended Dosage of Anastrozole?

Your dose is set by your oncologist and should always follow their instructions and your pharmacy label. Anastrozole is a tablet swallowed whole, usually once a day at about the same time each day, with or without food. Your care team will tell you how long to take it. Treatment often lasts several years.

Your care team may adjust the dose or schedule based on:

• Your condition: The length of treatment depends on the cancer type, stage, and your response.
• Liver function: No routine dose change is needed for mild liver problems. Severe liver impairment has not been well studied.
• Kidney function: No routine change is needed for most kidney problems.
• Other medicines: Some medicines can affect how well anastrozole works.
• Overall health: Age and other conditions can matter.

Do not change, skip, or stop doses on your own, even if you feel well.

How Anastrozole Works

Some breast cancers grow in response to the hormone estrogen. After menopause, most estrogen is made when an enzyme called aromatase changes other hormones into estrogen in fat, muscle, and other tissues.

Anastrozole blocks aromatase, which lowers estrogen levels in the body. With less estrogen, hormone-sensitive breast cancer cells may grow more slowly or be less likely to return. Anastrozole is used to control the disease or lower the chance of it coming back, and it is not considered a cure. Regular exams, imaging, and follow-up visits are an important part of care.

Is a Prescription Required to Buy Anastrozole Online?

Yes. Anastrozole is prescription-only. It should be prescribed and monitored by a licensed medical oncologist (a cancer specialist), often a breast cancer specialist, who may work with a breast surgeon or other members of your care team.

• Tests on the tumor are needed to confirm that it is hormone receptor-positive.
• Buy only from a licensed pharmacy that requires a valid prescription.
• Counterfeit or substandard medicines exist. Be cautious of websites that sell without a prescription or ship from unclear sources.
• Check that the tablets match what your pharmacist describes, and ask your pharmacist if packaging or appearance looks different.

Side Effects of Anastrozole

Not everyone gets every side effect. Many can be managed with help from your care team.

Common Side Effects

• Hot flashes
• Joint pain, stiffness, or muscle aches
• Weakness or tiredness
• Mood changes or trouble sleeping
• Headache
• Nausea
• Hair thinning
• Vaginal dryness
• Sore throat or mild swelling
• Higher cholesterol on blood tests

Serious Side Effects

These are less common but need prompt attention:

• Bone loss and fractures: anastrozole can lower bone density over time, which may lead to osteoporosis or broken bones
• Heart and blood vessel problems: chest pain, shortness of breath, or signs of a heart attack or stroke. Risk may be higher in people who already have heart disease.
• Severe allergic reaction: swelling of the face, lips, or throat, trouble breathing, or widespread rash
• Liver problems: yellowing of the skin or eyes, dark urine, severe stomach pain, or unusual tiredness
• Severe skin reactions: blistering, peeling skin, or mouth sores (rare)
• Nerve problems: numbness, tingling, or pain in the hands (carpal tunnel syndrome has been reported)

Seek immediate medical care if you have chest pain, trouble breathing, signs of stroke, swelling of the face or throat, or severe skin blistering. Contact your oncology team promptly for severe bone or joint pain, a fracture, vaginal bleeding, or any symptom that worries you.

Drug Interactions

Tell your oncologist and pharmacist about everything you take, including prescription drugs, over-the-counter (OTC) products, vitamins, supplements, and herbal products. Major categories include:

• Tamoxifen: Taking tamoxifen with anastrozole can lower anastrozole levels, and the two are not usually taken together.
• Estrogen-containing products: Hormone replacement therapy, estrogen creams or patches, and some birth control products may work against anastrozole.
• Other cancer medicines: Your oncologist will decide if and how anastrozole is combined with other treatments, such as CDK4/6 inhibitors.
• Herbal and soy products: Some supplements, such as black cohosh, red clover, or high-dose soy products, may act like estrogen. Ask your pharmacist before using any herbal or dietary supplement.
• Calcium and vitamin D: These are often recommended for bone health, but ask your care team what is right for you.

Bring a complete, updated medication list to every appointment.

Safety & Important Considerations

• Bone health: A bone density scan is often done before treatment and repeated as advised. Your team may recommend calcium, vitamin D, weight-bearing exercise, or bone-strengthening medicine.
• Cholesterol and heart health: Cholesterol may rise during treatment. Tell your team about any heart disease, high blood pressure, or high cholesterol.
• Liver disease: Liver blood tests may be checked during treatment. Discuss any liver problems with your specialist.
• Kidney disease: Little change is expected for most kidney problems. Discuss severe kidney disease with your specialist.
• Menopausal status: Anastrozole is approved only for postmenopausal women. If there is any doubt about menopausal status, your team may check hormone levels.
• Pregnancy: Anastrozole can harm an unborn baby. It is not for use during pregnancy. Women who could become pregnant may need a pregnancy test before treatment and effective contraception during treatment and for a period after the last dose. Tell your oncologist right away if you are or may become pregnant.
• Breastfeeding: Breastfeeding is not recommended during treatment and for a period after the last dose.
• Dizziness and tiredness: Use caution when driving or using machines until you know how anastrozole affects you.
• Older adults and children: Older adults take the same dose but are monitored for bone and heart health. Anastrozole is not approved for use in children.
• Monitoring: Expect regular visits, breast exams, imaging, and blood tests, including cholesterol.

Who This Medication Is For

Anastrozole is intended for postmenopausal women with hormone receptor-positive breast cancer, either early-stage cancer or advanced cancer, as decided by their oncology team. Treatment plans differ from person to person.

Who Should Not Take Anastrozole

Anastrozole should not be used by people with a known severe allergic reaction to anastrozole or any ingredient in the tablet. It is also not for use in women who are pregnant, and it is not suitable for premenopausal women.

Discuss with your oncologist before starting if you:

• Have had an allergic reaction to anastrozole or any tablet ingredient
• Are premenopausal, pregnant, planning pregnancy, or breastfeeding
• Have osteoporosis or a high risk of broken bones
• Have heart disease, high blood pressure, or high cholesterol
• Have liver disease or severe kidney disease
• Take medicines that interact with anastrozole, such as tamoxifen or estrogen products

What to Do If You Miss a Dose

• Take the missed dose as soon as you remember, unless it is almost time for your next dose. In that case, skip the missed dose and continue with your regular schedule.
• Never take two doses at once to make up for a missed one.
• If you are unsure what to do, or you miss several doses, contact your oncology team or pharmacist.

Related medications to Anastrozole

Other medicines are used for hormone receptor-positive breast cancer, depending on the cancer’s stage and features, your menopausal status, and your health:

• Other aromatase inhibitors: letrozole and exemestane
• Other hormone-based treatments: tamoxifen, fulvestrant, and newer oral hormone therapies
• Combination approaches: hormone therapy together with targeted medicines such as CDK4/6 inhibitors (abemaciclib, palbociclib, or ribociclib) in selected cases
• Other approaches: chemotherapy, surgery, and radiation

These medicines differ in side effects, interactions, and approved uses. Switching or combining treatments must be decided together with your oncologist.

Storage Instructions

• Store at room temperature, about 68°F to 77°F (20°C to 25°C), with brief trips between 59°F and 86°F (15°C to 30°C) allowed.
• Keep tablets in the original container with the lid tightly closed, away from moisture (not in the bathroom) and light.
• Keep out of reach of children and pets.
• Do not use tablets past the expiration date. Ask your pharmacist about safe disposal of unused medicine.
• Caregivers who are pregnant or planning pregnancy should ask the care team about handling precautions and should avoid handling crushed or broken tablets.

Disclaimer:

This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Patients must consult a licensed medical oncologist before starting, changing, or stopping treatment. Treatment decisions must be based on a full clinical evaluation by a qualified specialist.