Tamoxifen (Nolvadex) is a selective estrogen receptor modulator (SERM). It’s used to treat early stage and advanced or metastatic hormone receptor-positive (HR+) breast cancer in males and females. It’s also used to lower the risk for breast cancer in females who have a higher risk for breast cancer. Tamoxifen (Nolvadex) is an oral tablet that's taken by mouth, usually once a day. Common side effects of this medication include hot flashes, vaginal discharge, and swelling in the arms and legs, which might lead to weight gain. Brand name Nolvadex is no longer available.
Early-stage HR+ breast cancer after surgery to lower the risk of breast cancer coming back
Ductal carcinoma in situ (DCIS) in females after breast surgery and radiation to lower the risk of breast cancer coming back
Lowering the risk of breast cancer in females who are considered high risk
Tamoxifen (Nolvadex) is a selective estrogen receptor modulator (SERM). Some breast cancers depend on hormones like estrogen to grow. These breast cancers are called hormone receptor-positive (HR+).
Tamoxifen (Nolvadex) treats HR+ breast cancer by blocking estrogen from working on breast cancer tissue. By doing so, tamoxifen (Nolvadex) prevents cancer cells from getting the fuel needed to grow, and stops the cancer from spreading.
Source: DailyMed
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
bladder pain
blindness
bloating or swelling of the face, arms, hands, lower legs, or feet
bloody or cloudy urine
blurred vision
chills
confusion
decrease in the amount of urine
decrease in height
decreased vision
difficult or labored breathing
difficult, burning, or painful urination
dizziness
fainting
fast heartbeat
frequent urge to urinate
heavy non-menstrual vaginal bleeding
hoarseness
increased clear or white vaginal discharge
lower back or side pain
noisy, rattling breathing
pain in the back, ribs, arms, or legs
painful or difficult urination
pale skin
rapid weight gain
rapid, shallow breathing
stopping of menstrual bleeding
tightness in the chest
tingling of the hands or feet
troubled breathing at rest
troubled breathing with exertion
unusual bleeding or bruising
unusual tiredness or weakness
unusual weight gain or loss
Less common
Abnormal growth filled with fluid or semisolid material
black, tarry stools
bleeding gums
blurred vision
breast pain, redness, or swelling
clear or bloody discharge from the nipple
cough producing mucus
dimpling of the breast skin
feeling of warmth or heat
flushing or redness of the skin, especially on the face and neck headache
inverted nipple
joint pain or stiffness
large amount of cholesterol in the blood
lump in the breast or under the arm
nervousness
persistent crusting or scaling of the nipple
pinpoint red spots on the skin
pounding in the ears
skin rash or itching over the entire body
slow heartbeat
sore on the skin of the breast that does not heal
stomach or pelvic discomfort, aching, or heaviness
Incidence not known
Blistering, peeling, loosening of the skin
dark urine
general feeling of discomfort or illness
indigestion
large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or genitals
loss of appetite
pains in the stomach, side, or abdomen, possibly radiating to the back
red skin lesions, often with a purple center
red, irritated eyes
sores, ulcers, or white spots in the mouth or on the lips
thickening of bronchial secretions
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
Back pain
belching
body aches or pain
bone pain
congestion
difficulty in moving
dryness of the throat
hair loss or thinning of hair
joint swelling
lack or loss of strength
mood changes
muscle cramps or stiffness
passing of gas
redness of the face, neck, arms, and occasionally, upper chest
shivering
skin changes
stomach upset, fullness, or pain
sudden sweating
tender, swollen glands in the neck
trouble in swallowing
trouble sleeping
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.
Usually taken once a day
Oral tablet is available as a lower-cost generic
Might help prevent bone loss (osteoporosis) after menopause
Might raise your risk for blood clots, uterine cancer, and cataracts
Can’t take while pregnant or breastfeeding
Usually taken long term (at least 5 years)
Tamoxifen (Nolvadex) can be taken with or without food.
Tamoxifen (Nolvadex) can interact with other medications, herbals, and food products. For example, drinking alcohol while taking tamoxifen (Nolvadex) might prevent tamoxifen (Nolvadex) from working well to treat your cancer.
It's best to avoid drinking alcohol while you're taking tamoxifen (Nolvadex). Doing so can worsen certain side effects of tamoxifen (Nolvadex), such as hot flashes. Drinking can raise the level of estrogen in the body, and cause tamoxifen (Nolvadex) to not work as well in treating cancer. If stopping alcohol is difficult for you, talk with your care team so they can recommend resources to help you quit.
Tamoxifen (Nolvadex) can cause hot flashes. Talk with your oncologist if these symptoms are very uncomfortable. They can recommend ways to ease your symptoms, such as wearing loose fitting layers that you can remove easily and drinking more water throughout the day, instead of alcohol or caffeine.
You might experience swelling in the arms and legs (edema) after starting tamoxifen (Nolvadex). To ease swelling, consider wearing compression stockings to keep your blood flowing. Choosing a low-salt diet can also help.
In rare situations, tamoxifen (Nolvadex) can cause blood clots, even 2 to 3 months after stopping the medication. If you notice symptoms of blood clots, such as pain or swelling in your arms and legs, chest pain, or severe headache, get medical help right away.
In very rare cases, people taking tamoxifen (Nolvadex) for breast cancer developed cancer in the uterus later on. If you notice signs of uterine cancer, such as unusual vaginal discharge, bleeding or spotting, stomach pain, let your oncologist know. You'll need immediate medical attention.
Talk with your oncologist if you're thinking about breastfeeding. Tamoxifen (Nolvadex) can pass into breast milk, which might pose a risk to breastfeeding infants. Because of this risk, you shouldn’t breastfeed while taking tamoxifen (Nolvadex) and for 3 months after your last dose.
Tamoxifen (Nolvadex) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Risk factors: Receiving chemotherapy at the same time | Past blood clots
Tamoxifen (Nolvadex) can raise your risk of blood clots. Blood clots can develop in any part of the body, including in the veins in your legs (deep venous thrombosis), lungs (pulmonary embolism) and brain (stroke). In clinical studies, people have reported blood clots anytime between 1 month to 5 years after starting treatment. This risk is higher for people receiving tamoxifen (Nolvadex) at the same time as chemotherapy. If you’re having symptoms of blood clots, which can include swelling, pain, or redness in your legs, difficulty breathing, or chest pain, seek medical attention right away.
Risk factors: Taking tamoxifen for 2 years or longer
Though not common, there have been reports of people developing ovarian cysts, uterine fibroids, and uterine cancer after starting tamoxifen (Nolvadex). The reason for this isn’t fully understood, but it’s thought that tamoxifen (Nolvadex) acts like estrogen and can cause changes to the lining of the uterus. After you start tamoxifen (Nolvadex), your oncologist might ask you to get yearly gynecology exams. Let your healthcare provider know if you have any abnormal vaginal bleeding or bloody discharge, changes in your period, and pain or pressure in the area below your belly button (pelvis). These can be signs of uterine cancer. If you’ve had surgery to remove the uterus, you aren’t at risk for uterine cancer.
Tamoxifen (Nolvadex) can raise your chance of developing cataracts and other eye problems. Let your provider know if you experience any changes in your vision, like slow blurring of your vision or changes in how you see color.
Tamoxifen (Nolvadex) might cause changes in liver enzyme levels. On rare occasions, people have reported serious liver problems and liver cancer, which can be life-threatening. Your healthcare provider will monitor your liver health regularly through blood draws while you're taking tamoxifen (Nolvadex). If you develop liver problems, your healthcare provider might stop your treatment. Let your provider know if you experience yellowing of the eyes or skin, loss of appetite, or tiredness, as these can be signs of liver problems.
Some people taking tamoxifen (Nolvadex) for metastatic breast cancer that has spread to the bones have reported high blood calcium levels within a few weeks of starting treatment. Your oncologist might check your blood calcium level regularly after you start tamoxifen (Nolvadex). If your level is very high, they’ll ask you to stop this medication. Symptoms of high blood calcium levels can include nausea, tiredness, and muscle weakness.
Though rare, some people have reported low platelet count after starting tamoxifen (Nolvadex). It’s unclear whether the low platelet count is caused by tamoxifen (Nolvadex) or by other factors. But having a low platelet level raises your risk for bleeding. Your oncologist will check your blood counts regularly to see if your levels are within a safe range. Let your healthcare team know if you notice bruises that won’t go away or bleeding that’s difficult to stop because these might be signs of low platelet count.
Tamoxifen (Nolvadex) can cause serious harm to an unborn baby. If you’re able to become pregnant, you should use non-hormonal birth control, like condoms or a diaphragm, while taking tamoxifen (Nolvadex) and for 2 months after the last dose. Let your provider know right away if you become pregnant during this time.
Metastatic HR+ breast cancer: The typical dosing is 20 mg to 40 mg by mouth once daily. If your total daily dose is higher than 20 mg, your oncologist will ask you to divide it into 2 smaller doses and take it by mouth twice daily in the morning and evening.
Early stage HR+ breast cancer after surgery: The typical dosing is 20 mg by mouth once daily for 5 to 10 years.
Ductal carcinoma in situ (DCIS): The typical dosing is 20 mg by mouth once daily for 5 years.
Lowering the risk of getting breast cancer: The typical dosing is 20 mg by mouth once daily for 5 years.
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.
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.
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.
Females at high risk of developing breast cancer, and either currently taking warfarin (Coumadin) or have had blood clots in the past
Early-stage HR+ breast cancer after surgery to lower the risk of breast cancer coming back
Ductal carcinoma in situ (DCIS) in females after breast surgery and radiation to lower the risk of breast cancer coming back
Lowering the risk of breast cancer in females who are considered high risk
Metastatic HR+ breast cancer or tumors in which estrogen status is not known in postmenopausal females
Hormone receptor (HR)-positive, advanced or metastatic breast cancer
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American College of Obstetricians and Gynecologists. (2023). Endometrial cancer.
Committee on Gynecologic Practice. (2024). Tamoxifen and uterine cancer. American College of Obstetricians and Gynecologists.
Cuzick, J., et al. (2019). Use of anastrozole for breast cancer prevention (IBIS-II): Long-term results of a randomised controlled trial. The Lancet.
Fisher, B., et al. (2005). Tamoxifen for the prevention of breast cancer: Current status of the National Surgical Adjuvant Breast and Bowel Project P-1 study. Journal of the National Cancer Institute.
Ghanavati, M., et al. (2023). Tamoxifen use and risk of endometrial cancer in breast cancer patients: A systematic review and dose-response meta-analysis. Cancer Reports.
Mayne Pharma Commercial LLC. (2023). Tamoxifen citrate tablet, film coated [package insert]. DailyMed.
National Comprehensive Cancer Network. (2024). Ductal carcinoma in situ.
National Comprehensive Cancer Network. (2024). Invasive breast cancer.
Park, J., et al. (2014). Pattern alopecia during hormonal anticancer therapy in patients with breast cancer. Annals of Dermatology.
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