Tamoxen



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Generic Name: tamoxifen
(ta MOX i fen)

What is Tamoxen?

Tamoxen blocks the actions of estrogen, a female hormone. Certain types of breast cancer require estrogen to grow.

Tamoxen is used to treat and prevent some types of breast cancer.

Tamoxen may also be used for other purposes not listed in this medication guide.

What is the most important information I should know about Tamoxen?

Do not use this medication without telling your doctor if you are pregnant. It could cause harm to the unborn baby. Use an effective form of birth control, and tell your doctor if you become pregnant during treatment.

Before using Tamoxen, tell your doctor if you are allergic to any drugs, or if you have liver disease, high triglycerides (fatty acids) in your blood, a history of cataract, or a history of stroke or blood clot. Also tell your doctor if you if you are receiving chemotherapy or radiation treatment.

If you are taking Tamoxen to reduce your risk of breast cancer, you may need to take your first dose while you are having a menstrual period. You may also need to have a pregnancy test before you start taking tamoxifen, to make sure you are not pregnant. Follow your doctor's instructions.

Taking Tamoxen may increase your risk of uterine cancer, stroke, or a blood clot in the lung, which can be fatal. Talk with your doctor about your specific risks in taking this medication.

To be sure this medication is not causing harmful effects, your doctor may want you to have mammograms and to perform routine breast self exams on a regular basis. Your liver function may also need to be tested. Do not miss any scheduled visits to your doctor.

What should I discuss with my healthcare provider before taking Tamoxen?

Do not use this medication if you are allergic to Tamoxen.

If you have any of these other conditions, you may need a dose adjustment or special tests to safely use this medication:

  • liver disease
  • high levels of triglycerides (fatty acids) in your blood
  • a history of stroke or blood clot
  • a history of cataract; or
  • if you are receiving chemotherapy or radiation treatment.

Taking Tamoxen may increase your risk of uterine cancer, stroke, or a blood clot in the lung, which can be fatal. Talk with your doctor about your specific risks in taking this medication.

FDA pregnancy category D. This medication can cause harm to an unborn baby. Do not use Tamoxen without your doctor's consent if you are pregnant. Tell your doctor if you become pregnant during treatment. Use a non-hormonal form of birth control (such as a condom or a diaphragm and spermicide) while you are using this medication and for 2 months after your treatment ends.

It is not known whether Tamoxen passes into breast milk or if it could harm a nursing baby. This medication may also slow breast milk production. Do not use this medication without telling your doctor if you are breast-feeding a baby.

How should I take Tamoxen?

Take this medication exactly as it was prescribed for you. Do not take the medication in larger amounts, or take it for longer than recommended by your doctor. Follow the directions on your prescription label.

Take this medication with a full glass (8 ounces) of water.

Tamoxen can be taken with or without food.

If you are taking Tamoxen to reduce your risk of breast cancer, you may need to take your first dose while you are having a menstrual period. You may also need to have a pregnancy test before you start taking tamoxifen, to make sure you are not pregnant. Follow your doctor's instructions.

It is important to use Tamoxen regularly to get the most benefit. Get your prescription refilled before you run out of medicine completely. You may need to keep using this medication for up to 5 years.

To be sure this medication is not causing harmful effects, your doctor may want you to have mammograms and to perform routine breast self exams on a regular basis. Your liver function may also need to be tested. Do not miss any scheduled visits to your doctor.

Store Tamoxen at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and take the medicine at the next regularly scheduled time. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention if you think you have used too much of this medicine.

An overdose of Tamoxen is not expected to produce life-threatening symptoms.

What should I avoid while taking Tamoxen?

Follow your doctor's instructions about any restrictions on food, beverages, or activity while you are using Tamoxen.

What are the possible side effects of Tamoxen?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using Tamoxen and call your doctor at once if you have any of these serious side effects:

  • sudden numbness or weakness, especially on one side of the body
  • sudden headache, confusion, problems with vision, speech, or balance
  • chest pain, shortness of breath, or coughing up blood
  • pain or swelling in one or both legs
  • unusual vaginal bleeding or discharge
  • irregular menstrual periods
  • pain or pressure in your pelvic area
  • fever, chills, body aches, flu symptoms
  • pale skin, easy bruising or bleeding
  • new breast lumps; or
  • nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Less serious side effects may include:

  • hot flashes, warmth or tingly feeling under your skin
  • bone, joint, or tumor pain
  • redness or skin changes
  • swelling in your hands or feet
  • vaginal itching or dryness
  • depressed mood, weakness
  • weight loss
  • nausea
  • cough, sore throat
  • decreased sex drive, impotence, or difficulty having an orgasm
  • headache, dizziness; or
  • thinning hair.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Tamoxen?

Many drugs can interact with Tamoxen. Below is just partial list. Tell your doctor if you are using any of these medications:

  • aminoglutethimide (Cytadren)
  • bromocriptine (Parlodel)
  • cimetidine (Tagamet)
  • clozapine (Clozaril, FazaClo)
  • isoniazid (for treating tuberculosis)
  • letrozole (Femara)
  • methimazole (Tapazole)
  • nicardipine (Cardene)
  • pioglitazone (Actos)
  • rifampin (Rifadin, Rifater, Rifamate, Rimactane)
  • ropinirole (Requip)
  • ticlopidine (Ticlid)
  • a blood thinner (warfarin, Coumadin)
  • anti-malaria medication such as chloroquine (Arelan), pyrimethamine (Daraprim), or quinine (Qualaquin)
  • HIV or AIDS medicine such as delavirdine (Rescriptor) or ritonavir (Norvir)
  • an antibiotic such as terbinafine (Lamisil)
  • a heart rhythm medication such as amiodarone (Cordarone, Pacerone) or quinidine (Quinidex, Quin-Release Quin-G)
  • medicine to treat psychiatric disorders, such as chlorpromazine (Thorazine), haloperidol (Haldol), or thioridazine (Mellaril); or
  • an antidepressant such as bupropion (Wellbutrin), clomipramine (Anafranil), desipramine (Norpramin), duloxetine (Cymbalta), fluoxetine (Prozac), imipramine (Tofranil), paroxetine (Paxil), sertraline (Zoloft), or tranylcypromine (Parnate).

This list is not complete and there may be other drugs that can interact with Tamoxen. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.

Where can I get more information?

Your pharmacist can provide more information about Tamoxen.


Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.