Pronunciation:

ta-MOX-i-fen

Brand Names:

• Nolvadex
• Soltamox

Dosage Forms:

• Solution
• Tablet

Warnings:

Serious, life-threatening, and fatal events from use of tamoxifen include uterine malignancies, stroke, and pulmonary embolism. Discuss risks and benefits of tamoxifen with women at high risk for breast cancer and women with ductal carcinoma in situ (DCIS) when considering tamoxifen use to reduce the risk of developing breast cancer. For most patients already diagnosed with breast cancer, the benefits of tamoxifen outweigh its risks .

Serious and life-threatening uterine malignancies, stroke, and pulmonary embolism have been associated with tamoxifen use in the risk reduction setting (women with Ductal Carcinoma in Situ (DCIS) and women at high risk for breast cancer). Some of these adverse events were fatal. Health care providers should discuss the potential benefits versus the potential risks of these serious events with women at high risk of breast cancer and women with DCIS considering tamoxifen to reduce their risk of developing breast cancer. The benefits of tamoxifen outweigh its risks in women already diagnosed with breast cancer .

Classifications:

Therapeutic—

Antiestrogen

Uses of This Medicine:

Tamoxifen is used to treat certain types of breast cancer (eg, estrogen receptor-positive breast cancer that has spread to other parts of the body [metastatic], early stage estrogen receptor-positive breast cancer after surgery and radiation treatment). It is also used to reduce the risk of invasive breast cancer in adult women with ductal carcinoma in situ (DCIS) after breast surgery and radiation treatment.

Tamoxifen is also used to reduce the risk for breast cancer in women with a high chance of getting it. The following are risk factors that may increase your risk of developing breast cancer:

• If you have close family members (mother, sister, or daughter) with breast cancer.
• If you have ever had a breast biopsy or if high-risk changes in your breast(s) have been found from a breast biopsy.
• If you have never been pregnant or if your first pregnancy occurred at a late age.
• If your first menstrual period occurred at an early age.

Female hormones called estrogen, that occur naturally in the body can increase the growth of some breast cancers. Tamoxifen works by blocking the effects of estrogen in the body.

This medicine is available only with your doctor's prescription.

Before Using This Medicine:

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.

Children—

Appropriate studies have not been performed on the relationship of age to the effects of tamoxifen in the pediatric population. Safety and efficacy have not been established.

Older adults—

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of tamoxifen in the elderly.

Breast-feeding—

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Other medicines—

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

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.

• Acenocoumarol
• Bacillus of Calmette and Guerin Vaccine, Live
• Bepridil
• Cisapride
• Dengue Tetravalent Vaccine, Live
• Dronedarone
• Fluconazole
• Ketoconazole
• Lefamulin
• Levoketoconazole
• Mavorixafor
• Measles Virus Vaccine, Live
• Mesoridazine
• Mumps Virus Vaccine, Live
• Phenprocoumon
• Pimozide
• Piperaquine
• Posaconazole
• Rubella Virus Vaccine, Live
• Saquinavir
• Smallpox Monkeypox Vaccine
• Sparfloxacin
• Terfenadine
• Thioridazine
• Typhoid Vaccine
• Varicella Virus Vaccine
• Warfarin
• Yellow Fever Vaccine
• Ziprasidone

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.

• Abametapir
• Abiraterone Acetate
• Abiraterone Acetate, Micronized
• Adagrasib
• Adenovirus Vaccine Type 4, Live
• Adenovirus Vaccine Type 7, Live
• Amiodarone
• Amisulpride
• Anagrelide
• Apomorphine
• Aripiprazole
• Aripiprazole Lauroxil
• Arsenic Trioxide
• Asciminib
• Atazanavir
• Avacopan
• Azathioprine
• Azithromycin
• Bedaquiline
• Berotralstat
• Buprenorphine
• Bupropion
• Buserelin
• Capecitabine
• Carbamazepine
• Celecoxib
• Ceritinib
• Chloroquine
• Cholera Vaccine
• Cinacalcet
• Citalopram
• Clarithromycin
• Clobazam
• Clofazimine
• Clothiapine
• Clozapine
• Conivaptan
• Crizotinib
• Cyclophosphamide
• Dabrafenib
• Dacomitinib
• Daridorexant
• Darunavir
• Dasatinib
• Degarelix
• Delamanid
• Desflurane
• Deslorelin
• Desvenlafaxine
• Deutetrabenazine
• Dexmedetomidine
• Domperidone
• Donepezil
• Doxepin
• Doxifluridine
• Duloxetine
• Ebola Zaire Vaccine, Live
• Efavirenz
• Enasidenib
• Encorafenib
• Entrectinib
• Enzalutamide
• Escitalopram
• Etrasimod
• Fedratinib
• Fexinidazole
• Fingolimod
• Fluoroestradiol F 18
• Fluorouracil
• Fluoxetine
• Fluvoxamine
• Formoterol
• Foscarnet
• Fosnetupitant
• Fosphenytoin
• Fostemsavir
• Genistein
• Gepirone
• Givinostat
• Glasdegib
• Gonadorelin
• Goserelin
• Histrelin
• Hydroxychloroquine
• Hydroxyzine
• Iloperidone
• Influenza Virus Vaccine, Live
• Inotuzumab Ozogamicin
• Ipriflavone
• Isoflurane
• Itraconazole
• Ivabradine
• Ivosidenib
• Lanreotide
• Lazertinib
• Lenvatinib
• Letermovir
• Leuprolide
• Levofloxacin
• Lofexidine
• Lonafarnib
• Lumacaftor
• Macimorelin
• Mercaptopurine
• Methadone
• Methotrexate
• Metronidazole
• Mirtazapine
• Mitomycin
• Mitotane
• Mobocertinib
• Moclobemide
• Moxifloxacin
• Nafarelin
• Nelfinavir
• Netupitant
• Nilotinib
• Nirogacestat
• Octreotide
• Olanzapine
• Omaveloxolone
• Ondansetron
• Osilodrostat
• Osimertinib
• Oxaliplatin
• Ozanimod
• Pacritinib
• Palbociclib
• Paliperidone
• Panobinostat
• Paroxetine
• Pasireotide
• Pazopanib
• Peginterferon Alfa-2b
• Phenobarbital
• Phenytoin
• Pimavanserin
• Pitolisant
• Ponesimod
• Primidone
• Promethazine
• Quetiapine
• Quinine
• Quizartinib
• Red Clover
• Relugolix
• Repotrectinib
• Revumenib
• Ribociclib
• Rifampin
• Rilpivirine
• Rolapitant
• Rotavirus Vaccine, Live
• Selpercatinib
• Sertraline
• Sevoflurane
• Siponimod
• Solifenacin
• Sotalol
• Sotorasib
• St John's Wort
• Sulpiride
• Sunitinib
• Suzetrigine
• Tacrolimus
• Taurursodiol
• Tazemetostat
• Tegafur
• Tocilizumab
• Tovorafenib
• Trazodone
• Treosulfan
• Triclabendazole
• Triptorelin
• Tucatinib
• Vandetanib
• Vardenafil
• Vemurafenib
• Venlafaxine
• Vilanterol
• Vinflunine
• Voclosporin
• Vonoprazan
• Vorasidenib
• Zuclopenthixol

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
• Mavacamten

Other interactions—

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other medical problems—

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Blood clots (eg, deep vein thrombosis, pulmonary embolism) or history of—Should not be used in patients with this condition.

• Eye or vision problems (eg, cataracts) or
• Hypercalcemia (high calcium levels in the blood) or
• Hyperlipidemia (high cholesterol levels in the blood) or
• Liver disease or
• Stroke, history of—Use with caution. May make these conditions worse.

Proper Use of This Medicine:

Use this medicine only as directed by your doctor. Do not use more of it, do not use it more often, and do not take it for a longer time than your doctor ordered.

Medicines used to treat cancer are very strong and can have many side effects. Before using 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.

This medicine comes with a Medication Guide. Read and follow these instructions carefully. Ask your doctor if you have any questions.

Shake the oral liquid well before each use. Measure the medicine with a marked medicine cup. The average household teaspoon may not hold the right amount of liquid.

You may take this medicine with or without food. Swallow the tablets whole with a glass of water or other non-alcoholic liquid at about the same time each day.

Tamoxifen sometimes causes mild nausea and vomiting. However, it may have to be taken for several weeks or months to be effective. Even if you begin to feel ill, do not stop using this medicine without first checking with your doctor. Ask your health care professional for ways to lessen these effects.

Dosing—

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage form (solution or tablets):
  • For breast cancer:
    • Adults—20 to 40 milligrams (mg) per day. Doses greater than 20 mg are given as 2 divided doses per day (morning and evening).
    • Children—Use and dose must be determined by your doctor.
  • For breast cancer as additional treatment:
    • Adults—20 milligrams (mg) per day for 5 years.
    • Children—Use and dose must be determined by your doctor.
  • For reducing the risk of developing breast cancer in high-risk women:
    • Adults—20 milligrams (mg) per day for 5 years.
    • Children—Use and dose must be determined by your doctor.
  • For reducing the risk of developing invasive breast cancer in women with ductal carcinoma in situ:
    • Adults—20 milligrams (mg) per day for 5 years.
    • Children—Use and dose must be determined by your doctor.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Do not store the oral liquid in the refrigerator or freezer. Throw away any unused liquid after 3 months of first opening the bottle.

Precautions While Using This Medicine:

It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Do not use this medicine together with blood thinners (eg, warfarin).

Using this medicine while you are pregnant can harm your unborn baby. If you can get pregnant, your doctor may give you a pregnancy test before you start using this medicine to make sure you are not pregnant. Birth control pills may not work as well to prevent pregnancy when used with this medicine. Use another form of birth control (eg, condoms, spermicide) along with your pills during treatment and for 2 months after the last dose. If you think you have become pregnant while using the medicine, tell your doctor right away.

This medicine may increase your risk for other cancers, including endometrium, liver, or uterus cancer. Tell your doctor if you have any changes in your menstrual period, including irregular menstrual periods or no menstrual periods, or abnormal vaginal bleeding. It is important for women to have regular gynecologic check-ups while using this medicine. Talk to your doctor if you have concerns.

This medicine may increase your risk of developing blood clots or stroke. Check with your doctor right away if you have difficulty speaking, double vision, headache, inability to move the arms, legs, or facial muscles, swelling and pain in your arms, legs, or stomach, chest pain, loss of sensation, confusion, slow speech, trouble breathing, or problems with muscle control or speech.

This medicine may lower the number of some types of blood cells in your body. Because of this, you may bleed or get infections more easily. To help with these problems, avoid being near people who are sick or have infections. Wash your hands often. Stay away from rough sports or other situations where you could be bruised, cut, or injured. Brush and floss your teeth gently. Be careful when using sharp objects, including razors and fingernail clippers.

Check with your doctor right away if blurred vision, difficulty with reading, or any other change in vision occurs during or after treatment. Your doctor may want your eyes be checked by an ophthalmologist (eye doctor).

Check with your doctor right away if you have pain or tenderness in the upper stomach, dark urine or pale stools, or yellow eyes or skin. These could be symptoms of a serious liver problem.

Make sure any doctor or dentist who treats you knows that you are using this medicine. This medicine may affect the results of certain medical tests.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

Absent, missed, or irregular menstrual periods

back pain

bladder pain

bloating or swelling of the face, arms, hands, lower legs, or feet

bloody or cloudy urine

blurred vision

bone pain

chest pain or tightness

chills

clear or bloody discharge from the nipple

confusion

cough

decrease in the amount of urine

decrease in height

decreased vision

difficult or labored breathing

difficult, burning, or painful urination

dimpling of the breast skin

discouragement

dizziness

fainting

fast heartbeat

feeling of warmth or heat

feeling sad or empty

fever

flushing or redness of the skin, especially on the face and neck headache

frequent urge to urinate

headache

heavy non-menstrual vaginal bleeding

hoarseness

increased clear or white vaginal discharge

inverted nipple

irritability

lack of appetite

large amount of cholesterol in the blood

loss of interest or pleasure

lower back or side pain

lump in the breast or under the arm

muscle or joint pain

nervousness

noisy, rattling breathing

pain in the back, ribs, arms, or legs

painful or difficult urination

pale skin

persistent crusting or scaling of the nipple

pounding in the ears

rapid weight gain

rapid, shallow breathing

redness of the face, neck, arms, and occasionally, upper chest

slow or fast heartbeat

sore on the skin of the breast that does not heal

stomach pain

stopping of menstrual bleeding

sweating

swelling of the fingers, hands, feet, or lower legs

tingling of the hands or feet

trouble breathing

trouble concentrating

trouble sleeping

unusual bleeding or bruising

unusual tiredness or weakness

unusual weight gain or loss

white or brownish vaginal discharge

Less common

Abnormal growth filled with fluid or semisolid material

black, tarry stools

bleeding gums

bloating

breast pain, redness, or swelling

chest pain

cough producing mucus

joint stiffness

pinpoint red spots on the skin

skin rash or itching over the entire body

stomach or pelvic discomfort, aching, or heaviness

Rare

Anxiety

bluish color of the skin

changes in skin color

pain, redness, or swelling in the arm or leg

tenderness

Incidence not known

Blistering, peeling, loosening of the skin

constipation

dark urine

diarrhea

dry mouth

general feeling of discomfort or illness

incoherent speech

increased urination

indigestion

large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or genitals

metallic taste

muscle weakness

nausea

pains in the stomach, side, or abdomen, possibly radiating to the back

red skin lesions, often with a purple center

red, irritated eyes

sore throat

sores, ulcers, or white spots in the mouth or on the lips

thickening of bronchial secretions

thirst

vomiting

yellow eyes or skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Belching

body aches or pain

dryness of the throat

hair loss or thinning of hair

heartburn

joint swelling

lack or loss of strength

mood changes

muscle cramps or stiffness

passing of gas

shivering

skin changes

stomach upset, fullness, or pain

stuffy or runny nose

tender, swollen glands in the neck

trouble in swallowing

voice changes

Less common

Burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings

itching of the vagina or genital area

pain during sexual intercourse

Incidence not known

Decreased interest in sexual intercourse

inability to have or keep an erection

loss in sexual ability, desire, drive, or performance

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.