What is tamoxifen?

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Generic Name: Tamoxifen Brand Name(s): Generics only. No brands available.

Know the basics

What is tamoxifen used for?

Tamoxifen is used to treat breast cancer that has spread to other parts of the body (metastatic breast cancer), to treat breast cancer in certain patients after surgery and radiation therapy, and to reduce the chances of breast cancer in high-risk patients.

This medication can block the growth of breast cancer. It works by interfering with the effects of estrogen in the breast tissue.

How should I take tamoxifen?

Read the Medication Guide provided by your pharmacist before you start using tamoxifen and each time you get a refill. If you have any questions, consult your doctor or pharmacist.

Take this medication by mouth with or without food, usually once or twice daily for 5 years, or as directed by your doctor. Daily dosages greater than 20 milligrams are usually divided in half and taken twice a day, in the morning and evening, or as directed by your doctor. If you are using the liquid, measure the dose carefully using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.

Dosage is based on your medical condition and response to therapy.

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time(s) each day.

If you have breast cancer that has spread to other parts of the body, you may experience increased bone/cancer pain and/or disease flare-up as you start taking tamoxifen. In some cases, this may be a sign of a good response to the medication. Symptoms include increased bone pain, increased tumor size, or even new tumors. These symptoms usually disappear quickly. In any case, report these symptoms immediately to your doctor.

Since this drug can be absorbed through the skin and lungs, women who are pregnant or who may become pregnant should not handle this medication or breathe the dust from the tablets. (See also Precautions section.)

Inform your doctor immediately if your condition worsens (e.g., you get new breast lumps).

How do I store tamoxifen?

Tamoxifen is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store tamoxifen in the bathroom or the freezer. There may be different brands of tamoxifen that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush tamoxifen down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Know the precautions & warnings

What should I know before using tamoxifen?

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Geriatric

Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of tamoxifen in the elderly with use in other age groups, this medicine is not expected to cause different side effects or problems in older people than it does in younger adults.

Is it safe to take tamoxifen during pregnancy or breast-feeding?

There isn’t enough information about the safety of using this medication during pregnancy and breast-feeding. Please always consult with your doctor to weigh the potential benefits and risks before taking this medication.

Know the side effects

What are the side effects of tamoxifen?

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 tamoxifen and call your doctor at once if you have a serious side effect such as:

  • sudden numbness or weakness, especially on one side of the body;
  • sudden severe headache, confusion, problems with vision, speech, or balance;
  • chest pain, sudden cough, wheezing, rapid breathing, fast heart rate;
  • pain, swelling, warmth, or redness in one or both legs;
  • nausea, loss of appetite, increased thirst, muscle weakness, confusion, and feeling tired or restless;
  • unusual vaginal bleeding or discharge;
  • irregular menstrual periods;
  • pain or pressure in your pelvic area;
  • blurred vision, eye pain, or seeing halos around lights;
  • easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;
  • fever, chills, body aches, flu symptoms;
  • new breast lump; or
  • upper stomach pain, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Less serious side effects may include:

  • hot flashes;
  • bone pain, joint pain, or tumor pain;
  • swelling in your hands or feet;
  • vaginal itching or dryness;
  • decreased sex drive, impotence, or difficulty having an orgasm;
  • headache, dizziness, depression; or
  • thinning hair.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.

Know the interactions

What drugs may interact with tamoxifen?

Tamoxifen may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

  • Amifampridine
  • Fluconazole
  • Ketoconazole
  • Nelfinavir
  • Piperaquine
  • Posaconazole
  • Warfarin

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Abiraterone Acetate
  • Acenocoumarol
  • Anagrelide
  • Aprepitant
  • Aripiprazole
  • Buserelin
  • Carbamazepine
  • Ceritinib
  • Chlorpromazine
  • Clarithromycin
  • Clobazam
  • Cobicistat
  • Crizotinib
  • Cyclophosphamide
  • Dabrafenib
  • Delamanid
  • Desipramine
  • Deslorelin
  • Dicumarol
  • Domperidone
  • Escitalopram
  • Eslicarbazepine Acetate
  • Fluorouracil
  • Fluoxetine
  • Fluphenazine
  • Fluvoxamine
  • Fosaprepitant
  • Genistein
  • Gonadorelin
  • Goserelin
  • Histrelin
  • Idelalisib
  • Ipriflavone
  • Ivabradine
  • Leuprolide
  • Methotrexate
  • Metronidazole
  • Mitomycin
  • Mitotane
  • Moxifloxacin
  • Nafarelin
  • Nilotinib
  • Nitisinone
  • Ondansetron
  • Paroxetine
  • Pasireotide
  • Pazopanib
  • Phenprocoumon
  • Primidone
  • Quetiapine
  • Red Clover
  • Ritonavir
  • Sertraline
  • Sevoflurane
  • Siltuximab
  • St John’s Wort
  • Triptorelin
  • Vandetanib
  • Vemurafenib
  • Vinflunine

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Aldesleukin
  • Aminoglutethimide
  • Anastrozole
  • Bexarotene
  • Letrozole
  • Rifampin

Does food or alcohol interact with tamoxifen?

Tamoxifen may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with tamoxifen?

Tamoxifen may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have, especially:

For all patient

  • Blood problems or
  • Cataracts or other eye problems—Tamoxifen may also cause these problems.
  • High cholesterol levels in the blood—Tamoxifen can increase cholesterol levels.

When used for reducing the risk for developing breast cancer in high-risk women or in women with Ductal Carcinoma in Situ (DCIS)

  • Blood clots (or history of) or
  • Pulmonary embolism (or history of) or
  • Stroke or
  • Uterine (womb) cancer—May increase risk of serious side effects from tamoxifen.

Understand the dosage

The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using this medication.

What is the dose of tamoxifen for an adult?

Usual Adult Tamoxifen Dose for Breast Cancer:

For the treatment of metastatic breast cancer in women and men:

20 to 40 mg orally Dosages greater than 20 mg should be given in divided doses (morning and evening).

For the treatment of women with Ductal Carcinoma in Situ, following breast surgery and radiation:

20 mg orally daily for 5 years.

To reduce the incidence of breast cancer in women at high risk for breast cancer:

20 mg orally daily for 5 years.

Usual Adult Dose for Breast Cancer — Adjuvant:

For the treatment of node-positive breast cancer in postmenopausal women following total mastectomy or segmental mastectomy, axillary dissection, and breast irradiation:

10 mg orally 2 to 3 times a day for 5 years.

Usual Adult Tamoxifen Dose for Breast Cancer–Palliative:

10 to 20 mg orally twice a day

A beneficial response may not be evident for several months after initiation of therapy.

What is the dose of tamoxifen for a child?

Usual Pediatric Dose for McCune-Albright Syndrome:

For use in girls age 2 to 10 years with McCune-Albright Syndrome and precocious puberty:

20 mg once a day. The duration of treatment is up to 12 months.

Usual Pediatric Dose for Precocious Puberty:

For use in girls age 2 to 10 years with McCune-Albright Syndrome and precocious puberty:

20 mg once a day. The duration of treatment is up to 12 months.

How is tamoxifen available?

Tamoxifen is available in the following dosage forms and strengths:

Solution, oral: 10 mg/5 mL (150 mL)

Tablet: 10 mg; 20 mg

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

Symptoms of overdose may include:

  • uncontrollable shaking of a part of the body
  • unsteadiness
  • dizziness

What should I do if I miss a dose?

If you miss a dose of tamoxifen, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Sources

Review Date: May 30, 2016 | Last Modified: January 4, 2017

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