Tamoxifen, Oral

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KEY POINTS

• This medicine is taken by mouth to treat breast cancer. Take it exactly as directed.
• Keep all appointments for checkups and tests to see how this medicine affects you.
• This medicine may increase your risk for cancer of the uterus, cataracts, strokes, liver problems, and blood clots in the legs or lungs. This medicine may also cause other unwanted side effects. Tell your healthcare provider if you have any side effects that are serious, continue, or get worse.
• Tell all healthcare providers who treat you about all the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take.

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What are other names for this medicine?

Type of medicine: antineoplastic (anticancer); antiestrogen; selective estrogen receptor modulator (SERM)

Generic and brand names: tamoxifen, oral; Soltamox

What is this medicine used for?

This medicine is taken by mouth to:

• Treat breast cancer in men and women that has spread to other parts of the body (metastatic)
• Treat breast cancer in women who have already received early treatment with surgery, radiation, or chemotherapy to lower the chance of a spreading (metastatic) cancer or new breast cancer
• Lower the chance of getting a more serious (spreading) type of breast cancer in women who have already received surgery and radiation for ductal carcinoma in situ (DCIS; a type of cancer that is only in the milk ducts)
• Lower the chance of getting breast cancer in women with a higher than normal chance of getting breast cancer in the next 5 years (high-risk), due to their age, medical history, and family history

This medicine may be used to treat other conditions as determined by your healthcare provider.

What should my healthcare provider know before I take this medicine?

Before taking this medicine, tell your healthcare provider if you have ever had:

• An allergic reaction to any medicine
• A stroke or transient ischemic attack (TIA)
• Blood clots

Tell your healthcare provider if you are scheduled for major surgery or have recently had a long period of bed rest after a broken bone in a cast. This may increase your chance of blood clots.

Do not take this medicine if you are taking medicine that reduces the chance of blood clots forming such as warfarin (Coumadin).

Females of childbearing age: This medicine is not usually given to pregnant women because it can harm the baby. If you are pregnant, tell your healthcare provider. Talk to your healthcare provider if you need birth control. Birth control pills may not prevent pregnancy while you are taking this medicine. Do not become pregnant during treatment with this medicine or for 2 months after you stop taking this medicine. If you become pregnant, contact your healthcare provider right away. Do not breast-feed while you are receiving this medicine.

How do I take it?

Read the Medication Guide that comes in the medicine package when you start taking this medicine and each time you get a refill.

Check the label on the medicine for directions about your specific dose. Take this medicine exactly as your healthcare provider prescribes. Do not stop taking it, even if you feel better. You may have to take this medicine for a long time, sometimes for as long as 5 years.

You may take it with or without food. If you have the liquid form of this medicine, use a specially marked measuring device to measure each dose. The average household teaspoon may not hold the right amount of liquid.

What if I miss a dose?

If you miss a dose, use it as soon as you remember unless it is almost time for the next scheduled dose. In that case, skip the missed dose and use the next one as directed. Do not use double doses. If you are not sure of what to do if you miss a dose, or if you miss more than one dose, contact your healthcare provider.

What if I overdose?

If you or anyone else has intentionally taken too much of this medicine, call 911 or go to the emergency room right away. If you pass out, have seizures, weakness or confusion, or have trouble breathing, call 911. If you think that you or anyone else may have taken too much of this medicine, call the poison control center. Do this even if there are no signs of discomfort or poisoning. The poison control center number is 800-222-1222.

Symptoms of an acute overdose may include: unusual muscle movements, twitching, loss of balance, dizziness, irregular heartbeat, seizures.

What should I watch out for?

This medicine may increase your risk for cancer of the uterus, cataracts, strokes, liver problems, and blood clots in the legs or lungs. Contact your healthcare provider immediately if you notice abnormal vaginal bleeding, irregular or abnormal menstrual periods, groin pain or pressure, chest pain, pain or swelling in your legs, trouble breathing, changes in vision, yellowing of skin or eyes, or weakness on one side of your body.

Your healthcare provider will see you regularly while you are taking this medicine. You will need to have blood tests regularly to see how this medicine affects you. Keep all appointments for these tests.

You need to have regular eye exams while on this medicine because it may cause cataracts.

This medicine may cause dizziness. Do not drive or operate machinery unless you are fully alert.

This medicine may weaken your bones over time and increase your risk for bone fractures. Your healthcare provider may order tests to determine if this medicine is affecting your bones.

If you need emergency care, surgery, lab tests, or dental work, tell the healthcare provider or dentist you are taking this medicine.

What are the possible side effects?

Along with its needed effects, your medicine may cause some unwanted side effects. Some side effects may be very serious. Some side effects may go away as your body adjusts to the medicine. Tell your healthcare provider if you have any side effects that continue or get worse.

Life-threatening (Report these to your healthcare provider right away. If you cannot reach your healthcare provider right away, get emergency medical care or call 911 for help.): Allergic reaction (hives; itching; rash; trouble breathing; tightness in your chest; swelling of your lips, tongue, and throat); sudden weakness, numbness, or tingling, especially on one side of your body; sudden or severe headache; sudden trouble with vision, speech, balance, or walking.

Serious (Report these to your healthcare provider right away.): Abnormal vaginal itching, bleeding, or discharge; unusual tiredness or weakness; bone pain; pain or swelling in your legs; shortness of breath; vision changes; menstrual changes; chest pain; coughing blood; confusion; depression; weight gain; unusual bruising or bleeding; severe stomach pain; yellowing of your skin or eyes; dark urine; light-colored bowel movements.

Other: Dizziness, weakness, hot flashes, muscle and joint pain, hoarseness, mild headache, nausea, vomiting, loss of appetite, loss of taste for food (tell your healthcare provider if it is severe), change in sexual desire or ability, mood changes, trouble sleeping, constipation, diarrhea, swelling in hands or feet, hair thinning.

What products might interact with this medicine?

When you take this medicine with other medicines, it can change the way this or any of the other medicines work. Nonprescription medicines, vitamins, natural remedies, and certain foods may also interact. Using these products together might cause harmful side effects. Talk to your healthcare provider if you are taking:

• Bromocriptine (Cycloset, Parlodel)
• Bupropion (Aplenzin, Forfivo, Wellbutrin, Buproban, Zyban)
• Cancer medicines such as aldesleukin (Proleukin), anastrozole (Arimidex), cyclophosphamide (Cytoxan), and letrozole (Femara)
• Cinacalcet (Sensipar)
• Dextromethorphan/quinidine (Nuedexta)
• Fluoxetine (Prozac)
• HIV medicines such as delavirdine (Rescriptor), lopinavir/ritonavir (Kaletra), and tipranavir (Aptivus)
• Hormonal birth control implants, IUDs, patches, pills, shots, and vaginal rings, and estrogen hormones such as Cenestin, Estinyl, Estrace, Estraderm, Estratab, FemPatch, Premarin, and Vivelle
• Medroxyprogesterone (Depo-Provera, Provera)
• Natural remedies such as black cohosh, chasteberry, dong quai, melatonin, soy isoflavones, and St. John's wort
• Paroxetine (Brisdelle, Paxil, Pexeva)
• Phenobarbital
• Quinidine
• Rifabutin (Mycobutin) and rifampin (Rifadin)
• Terbinafine (Lamisil)
• Thioridazine
• Warfarin (Coumadin)

Do NOT eat or drink products that contain grapefruit, Seville oranges, and tangelos at any time while you are taking this medicine. These fruits and juices affect the way this medicine works and increase your risk of serious side effects. Talk with your healthcare provider or pharmacist about this.

If you are not sure if your medicines might interact, ask your pharmacist or healthcare provider. Keep a list of all your medicines with you. List all the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take. Be sure that you tell all healthcare providers who treat you about all the products you are taking.

How should I store this medicine?

Store this medicine at room temperature. Keep the container tightly closed. Protect it from heat, high humidity, and bright light.

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This advisory includes selected information only and may not include all side effects of this medicine or interactions with other medicines. Ask your healthcare provider or pharmacist for more information or if you have any questions.

Ask your pharmacist for the best way to dispose of outdated medicine or medicine you have not used. Do not throw medicine in the trash.

Keep all medicines out of the reach of children.

Do not share medicines with other people.