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Tamoxifen oral tablet dosage: A detailed guide

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Form and strengthsDosageFAQHow it’s takenCouponOverdoseAsk your doctorBoxed warning
Doctors prescribe tamoxifen oral tablet to treat and lower the risk of certain types of breast cancer. You take it by mouth one to two times per day.
Medically reviewed by Alex Brewer, PharmD, MBA
Updated on

This article describes tamoxifen oral tablet’s dosages and strengths and gives details on how to take it. You’ll also find information on cost savings and coupon options for tamoxifen. If you want to know more about tamoxifen oral tablet, see this overview article. It covers details about the drug’s uses and side effects, ways to save on cost, and more.

Tamoxifen oral tablet is a generic medication. It’s not available in a brand-name version. Tamoxifen also comes in a liquid solution, but that form isn’t described in this article. To learn more about that form, talk with your doctor.

Boxed warning: Risk of uterine cancer, stroke, or certain blood clots in some people

Tamoxifen has a boxed warning for the risk of uterine cancer, stroke, or certain blood clots in some people. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

See the end of this article for more information about this warning.

Form and strengths of tamoxifen

Tamoxifen oral tablet comes as follows:

  • Form: tablet that you swallow
  • Strengths: 10 milligrams (mg), 20 mg

Dosage of tamoxifen

This article describes the recommended dosages for tamoxifen oral tablet. The drugmaker provides these dosages.

If your doctor prescribes this medication, you should follow the dosage they prescribe. Your doctor will determine the dosage that best meets your needs. Do not change your dosage of tamoxifen oral tablet without your doctor’s recommendation.

Usual recommended dosages of tamoxifen in adults

The following table outlines the recommended dosages of tamoxifen oral tablet in milligrams (mg).

PurposeRecommended dosage
treat metastatic breast cancer (breast cancer that has spread to other parts of the body)20–40 mg per day, taken in one or two divided doses
reduce the risk of breast cancer coming back after the primary treatment, such as surgery20 mg daily, divided into one or two doses
reduce the risk of a type of breast cancer called ductal carcinoma in situ (DCIS) from spreading20 mg once per day
reduce the risk of breast cancer in people at high risk20 mg once per day

Dosage adjustments for tamoxifen

Your doctor will prescribe a dosage of tamoxifen oral tablet based on several factors. These include:

  • the specific condition being treated and how severe it is
  • your age
  • other health conditions you may have

Missed dose of tamoxifen

Talk with your doctor or pharmacist right away if you realize you forgot to take a dose of tamoxifen oral tablet. They may advise you to take the missed dose. Or they may advise you to skip it and take your next dose as scheduled.

For tips on how to plan your doses of tamoxifen oral tablet and avoid missing a dose, read this article. You could also try:

  • downloading a reminder app on your phone
  • setting an alarm
  • putting a note where you’ll see it, such as on your calendar, bathroom mirror, or bedside table

Frequently asked questions

Below are answers to some commonly asked questions about tamoxifen oral tablet and its dosage.

What is the lowest effective dose of tamoxifen?

In general, the lowest dosage of tamoxifen that’s prescribed is 20 milligrams (mg) per day. In some cases, your doctor may prescribe a lower dosage if you have certain medical conditions or take certain other medications.

If you have more questions about the lowest effective dose of tamoxifen, talk with your doctor.

Is tamoxifen taken long term?

Yes, doctors typically prescribe tamoxifen oral tablet as a long-term treatment. For example, studies indicate that it is most effective in lowering the risk of breast cancer when taken for 5 years. If you and your doctor determine that tamoxifen is safe and effective for your condition, you’ll likely take it long term.

If you have questions about how long you should take tamoxifen oral tablet, talk with your doctor.

How tamoxifen is taken

You’ll swallow tamoxifen oral tablet once or twice per day, as prescribed by your doctor. You can take the drug with or without food.

Your doctor may advise that you take this medication around the same time each day. This helps keep a consistent amount of the drug in your body. And that can help the drug work more effectively.

You should not cut or crush the tablets. If it’s hard for you to swallow tablets, view this article. It provides suggestions on how to swallow medications that come in pill form.

Also, be sure to talk with your doctor or pharmacist if you’re having difficulty taking your medication. They can offer recommendations about taking it.

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Overdose of tamoxifen

It’s important that you do not take more tamoxifen oral tablet than your doctor prescribes. Doing so can lead to harmful effects.

Symptoms of tamoxifen overdose

Symptoms of an overdose can include:

What to do if you take too much tamoxifen

If you think you’ve taken too much tamoxifen, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have severe symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.

What to ask your doctor

This article describes the usual recommended dosages for tamoxifen oral tablet. If your doctor prescribes this medication, they’ll determine the dosage that’s best for you.

Do not change your dosage of tamoxifen oral tablet without your doctor’s recommendation. You should take tamoxifen oral tablet exactly as your doctor prescribes it. Let your doctor know if you have concerns or questions about your treatment plan.

Here’s a list of some possible questions you may want to ask your doctor:

  • How long will I take tamoxifen oral tablet?
  • How does the dosage of tamoxifen oral tablet compare to other drugs for my condition?
  • Will my dosage of tamoxifen oral tablet change if I’m taking other drugs with it?

Boxed warning for tamoxifen

Tamoxifen has a boxed warning for the risk of uterine cancer, stroke, or certain blood clots in some people. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

This risk applies to anyone taking tamoxifen. But the risk might outweigh the benefit of using the drug to help prevent a certain type of breast cancer.

Risk of uterine cancer. Tamoxifen may increase your risk of uterine cancer. Uterine cancer starts in the inner lining of the uterus. One of the most common symptoms is abnormal vaginal bleeding.

Risk of stroke and some types of blood clots. Tamoxifen may raise your risk of stroke and blood clots in your lungs or veins. If you experience any symptoms of stroke or blood clots, call 911 or your local emergency number to get medical help right away.

Symptoms of stroke or blood clots include:

Talk with your doctor to learn more about these boxed warnings.

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

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