Letrozole (By mouth)
Treats breast cancer.
When This Medicine Should Not Be Used
How to Use This Medicine
- Medicines used to treat cancer are very strong and can have many side effects. Before receiving this medicine, make sure you understand all the risks and benefits. It is important for you to work closely with your doctor during your treatment.
- Your doctor will tell you how much medicine to use. Do not use more than directed.
- You may take this medicine with or without food.
If a dose is missed:
- This medicine needs to be given on a fixed schedule. If you miss a dose, call your doctor for instructions.
- If you vomit after taking your medicine, call your doctor or pharmacist for instructions.
How to Store and Dispose of This Medicine
- Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
- Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any leftover medicine after you have finished your treatment. You will also need to throw away old medicine after the expiration date has passed.
- Keep all medicine out of the reach of children. Never share your medicine with anyone.
Drugs and Foods to Avoid
Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.
- Make sure your doctor knows if you are also using tamoxifen (Nolvadex®).
Warnings While Using This Medicine
- It is not safe to take this medicine during pregnancy. It could harm an unborn baby. Tell your doctor right away if you become pregnant.
- Make sure your doctor knows if you are breastfeeding, or if you have severe liver disease or cirrhosis, bone problems (such as osteoporosis), or high cholesterol in the blood.
- This medicine may decrease bone mineral density when used for a long time. A low bone mineral density can cause weak bones or osteoporosis. If you have any questions about this, talk to your doctor.
- This medicine may increase your cholesterol or fat in the blood. If this happens, your doctor may give you medicine to lower the cholesterol and fat.
- This medicine may make you dizzy or drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert.
- Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments. Blood tests may be needed to check for unwanted effects.
Possible Side Effects While Using This Medicine
Call your doctor right away if you notice any of these side effects:
- Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
- Changes in vision.
- Chest pain, shortness of breath, or coughing up blood.
- Fast, irregular, or pounding heartbeat.
- Fever, chills, cough, sore throat, and body aches.
- Increase in how much or how often you urinate, painful urination.
- Numbness or weakness in your arm or leg, or on one side of your body.
- Pain in your lower leg (calf).
- Severe bone, joint, or back pain.
- Sudden or severe headache, problems with vision, speech, or walking.
- Swelling in your ankles or feet.
- Unusual bleeding or bruising.
- Unusual tiredness or weakness.
- Vaginal discharge, bleeding, or dryness.
If you notice these less serious side effects, talk with your doctor:
- Breast pain.
- Changes in appetite.
- Diarrhea, constipation, nausea, vomiting, or stomach pain.
- Hot flashes or increased sweating.
- Mild headache.
- Mild joint, back, or muscle pain.
- Skin rash.
- Trouble sleeping.
- Warmth or redness in your face, neck, arms, or upper chest.
- Weight gain or loss.
If you notice other side effects that you think are caused by this medicine, tell your doctor
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088
- Last reviewed on 1/27/2017
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