Risk-Reducing Drugs
Tamoxifen and raloxifene are the only drugs FDA-approved for breast cancer risk reduction in women who do not have breast cancer but are at higher risk.
You may hear the term “chemoprevention” to describe these drugs, but they are not chemotherapy drugs.
- Tamoxifen is used to prevent and treat breast cancer.
- Raloxifene is used to prevent breast cancer. (Raloxifene is also used to prevent and treat osteoporosis.)
Both tamoxifen and raloxifene are pills.
| For a summary of research studies on tamoxifen and raloxifene and breast cancer risk reduction, visit the Breast Cancer Research Studies section. |
Read our blog, Colleen’s Story: High Risk for Breast Cancer? Come Up With a Plan.
Tamoxifen and raloxifene
In women who are at higher risk of breast cancer, taking tamoxifen or raloxifene can lower risk.
Breast cancer risk
Both tamoxifen and raloxifene can lower the risk of [251]:
- Invasive breast cancer
- Non-invasive breast cancer, such as ductal carcinoma in situ (DCIS)
Tamoxifen and raloxifene only reduce the risk of estrogen receptor-positive breast cancers. Neither drug reduces the risk of estrogen receptor-negative breast cancers [251].
Tamoxifen is more effective than raloxifene in lowering breast cancer risk [251]. Tamoxifen lowers risk by about 50% in women at high risk [251].
Raloxifene lowers risk by about 38% in women at high risk [251]. However, raloxifene has fewer harmful side effects than tamoxifen (see table below) [251]. This makes raloxifene a better choice for some women.
Low-dose tamoxifen
Women who have trouble taking tamoxifen for risk reduction due to the side effects may consider taking low-dose tamoxifen for 3-5 years [55].
Side effects
Both tamoxifen and raloxifene have some long-term side effects (see table below) and may not be right for all women at higher risk. For example, tamoxifen increases the risk of cataracts and cancer of the uterus [251].
Talk with your health care provider about the possible benefits and harms of these drugs.
Learn more about the side effects of tamoxifen.
Learn more about talking with your health care provider.
Tamoxifen versus raloxifene for breast cancer risk reduction |
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Tamoxifen |
Raloxifene |
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Who can take the drug? |
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How is the drug taken? |
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What are common short-term side effects? |
Other side effects are less common. |
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What are the possible health risks? |
These effects occur mostly in older postmenopausal women. |
These effects occur mostly in older postmenopausal women. |
What about use in breast cancer treatment? |
Effective in the treatment of hormone receptor-positive breast cancer |
Not effective for breast cancer treatment |
Adapted from selected sources [251,391-396]. |
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Tamoxifen and antidepressants
Some types of antidepressants called selective serotonin reuptake inhibitors (SSRIs) can interfere with how tamoxifen works in the body. However, it is unlikely SSRIs reduce the effectiveness of tamoxifen [397-398].
If you’re taking an SSRI to treat depression or menopausal symptoms (such as hot flashes), talk with your health care provider about possible drug interactions.
BRCA1 and BRCA2 inherited gene mutations and tamoxifen
Researchers are studying the benefit of tamoxifen for women with a BRCA1 or BRCA2 inherited gene mutation who choose not to have a risk-reducing mastectomy.
Tamoxifen is likely better at preventing breast cancer in women with a BRCA2 gene mutation than in women with a BRCA1 gene mutation [218]. Tamoxifen only reduces the risk of estrogen receptor-positive cancers [251]. BRCA2-related tumors are more likely than BRCA1-related tumors to be estrogen receptor-positive [218].
Learn more about BRCA1 and BRCA2 mutations in women.
Learn about BRCA1 and BRCA2 mutations in men.
Race, ethnicity and tamoxifen
Most of what we know about the potential benefits and harms of tamoxifen come from data on white women. There are few data on women of other races or ethnicities.
However, some older studies show Black women are more likely than white women to suffer from some of the harmful health effects of tamoxifen [399-400].
Aromatase inhibitors
Aromatase inhibitors are hormone therapy drugs used to treat estrogen receptor-positive breast cancer in postmenopausal women. Aromatase inhibitors are pills.
Exemestane (Aromasin) and anastrozole (Arimidex)
Exemestane and anastrozole are aromatase inhibitor drugs. Findings from randomized controlled trials have shown exemestane and anastrozole may reduce the risk of breast cancer by about half for postmenopausal women at high risk [252-253].
Unlike tamoxifen and raloxifene, exemestane and anastrozole do not appear to increase the risk of blood clots [252-253]. However, they can cause menopausal symptoms, a loss of bone density and other side effects [252-253,401-404].
The American Society for Clinical Oncology (ASCO), the National Comprehensive Cancer Network (NCCN) and the U.S. Preventive Services Task Force list exemestane and anastrozole as risk-reducing drug options for postmenopausal women who do not have breast cancer, but are at high risk of breast cancer.
However, exemestane and anastrozole are not FDA-approved for use in the risk reduction setting. They are only FDA-approved for use in breast cancer treatment.
Learn about aromatase inhibitors (including exemestane and anastrozole) and breast cancer treatment.
Learn more about the side effects of aromatase inhibitors.
Other aromatase inhibitors
The aromatase inhibitor drug letrozole (Femara) is under study to see whether it lowers breast cancer risk in postmenopausal women at high risk.
Learn about aromatase inhibitors and breast cancer treatment.
Clinical trials of risk-reducing drugs
Some drugs currently used to treat breast cancer are under study for use in risk reduction and new risk-reducing drugs are being developed.
Learn more about emerging areas in breast cancer risk reduction.
Consider joining a clinical trial
If you’re at higher risk of breast cancer and considering joining a risk-reducing drug clinical trial, discuss the potential risks and benefits with your health care provider.
Susan G. Komen® Patient Care Center |
If you or a loved one needs information or resources about clinical trials, the Patient Care Center can help. Contact the Komen Breast Care Helpline at 1-877-465-6636 or email clinicaltrialinfo@komen.org. Se habla español. |
BreastCancerTrials.org in collaboration with Komen offers a custom matching service to help find breast cancer risk reduction clinical trials.
Learn more about clinical trials.
Prescription drug assistance
Medicare and many insurance companies offer prescription drug plans. One may already be included in your policy. Or you may be able to buy an extra plan for prescriptions.
You may also qualify for assistance from programs that help with drug costs. Other programs offer low-cost or free prescriptions.
Since September 2014, the Affordable Care Act has required insurance plans to cover the cost (with no co-payments) of tamoxifen and raloxifene for women at high risk of breast cancer. Learn more about this coverage.
Generic drugs are available. Generic drugs cost less than name brand drugs but are just as effective.
Learn more about insurance plans, prescription drug assistance programs and other financial assistance resources.
Susan G. Komen® Support Resources |
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Updated 11/07/26
This content is regularly reviewed by an expert panel including researchers, practicing clinicians and patient advocates.
