Hormonal therapy medicines treat hormone-receptor-positive breast cancer by lowering the amount of estrogen in the body or by blocking the action of estrogen on breast cancer cells. Most women take hormonal therapy for a total of 5 years, but some may take it for more time. Tamoxifen (brand name: Nolvadex) is one widely use hormonal therapy medicine. The aromatase inhibitors:

are another group of hormonal therapy medicines that are widely used to treat postmenopausal women.

Hot flashes and night sweats are side effects of both tamoxifen and the aromatase inhibitors, though they're more common with tamoxifen. Joint pain is a more common side effect of the aromatase inhibitors. Treatment with either tamoxifen or an aromatase inhibitor can lead to dangerous blood clots in rare cases. This complication is more common with tamoxifen. Also, aromatase inhibitors can weaken bones and make women more likely to break a bone.

Research suggests that exercise can help ease some hormonal therapy side effects, including joint pain from aromatase inhibitors.

During: Yes. First make sure you have your doctor’s OK to start. It’s also a good idea to visit a physical therapist well trained in diagnosing lymphedema for a structural evaluation before you start exercising (if you didn’t do this after surgery). Besides looking for lymphedema, a physical therapist can check for any other issues unrelated to breast cancer that may limit your ability to exercise. Learn how to find a lymphedema therapist .

In many cases, you take hormonal therapy after surgery. Some women may take it at the same time as radiation therapy, chemotherapy, or targeted therapy. If you take hormonal therapy after surgery, make sure you give yourself enough time to heal after surgery. See the recommendations for Exercise After Surgery for more information.

If you’re taking hormonal therapy at the same time as chemotherapy or radiation, follow these precautions:

If you’re experiencing extreme fatigue, anemia (low red blood cell count), or a lack of muscle coordination (ataxia), don’t exercise.

If your immune system is compromised and your white blood cell count is low (lower than 3,500 white blood cells per microliter of blood), avoid public gyms, yoga studios, and other public places until your white blood cell count is at a safe level.

If you have neuropathy in your hands or feet (pain or numbness from peripheral nerve damage) from chemotherapy, make sure you take care to reduce your risk of falling or injuring yourself.

If your risk of breaking a bone is higher than average (because of chemotherapy or an aromatase inhibitor), you may have to lower the intensity and duration of your workout. Talk to your doctor about the exercises you plan to do. You also may want to talk to a physical therapist or a certified trainer who has experience working with breast cancer survivors.

If you were on a chemotherapy or targeted therapy that may cause heart damage, make sure you ask your doctor or your cardiologist how long any side effects may last and what type of exercise modifications, if any, are right for you. It’s a good idea also to ask your doctor what the right intensity level is for your workouts and when you can increase it.

If you’re taking any hormonal therapy medicine to treat breast cancer that has spread to another part of the body away from the breast (metastatic breast cancer), especially cancer that has spread to the bone, you may have a higher risk of breaking a bone. Also, if you’re taking any one of the aromatase inhibitors, you also may be at higher risk of breaking a bone. In both cases, you may have to lower the intensity and duration of your workout. Talk to your doctor about the exercises you plan to do. You also may want to talk to a physical therapist or a certified trainer who has experience working with breast cancer survivors.

Some research suggests that some women taking hormonal therapy may be more likely to fall than other women their age. Take precautions to make sure you don’t hurt yourself, such as wearing sturdy athletic shoes and working out on a cushioned mat. You may want to have a spotter with you when you work out. Exercise can help improve your balance by strengthening your muscles.

Other Precautions: If you have any shortness of breath, pain, or tightness in your chest, stop exercising immediately. Tell your doctor what happened and work with him or her to develop a plan of movements that are right for you.

If you have any changes in your arm, hand, trunk, breast, or shoulder, including swelling, stop doing upper body exercises and see your doctor or lymphedema specialist. If you’ve been diagnosed with lymphedema after breast cancer treatment, there are precautions you should take before you exercise. These precautions include wearing a well-fitted compression garment or possibly wearing protective gloves. Learn more about exercise and lymphedema in the Lymphedema section.

After: Yes. Make sure you have your doctor’s OK to start.

If you have lymphedema or are at high risk for it, continue to watch for any changes in your arm, hand, trunk, breast, or shoulder. If you notice anything, stop doing upper body exercises and see your doctor or lymphedema specialist. Again, if you’ve been diagnosed with lymphedema, precautions include wearing a well-fitted compression garment and possibly protective gloves. Learn more in the Lymphedema section.

— Last updated on March 25, 2022, 6:48 PM

By submitting my email, I agree to receive newsletters from Breastcancer.org

A confirmation has been sent to your email address.