Breast Cancer Treatment Side Effects

There are many different ways that your body may respond to treatments for breast cancer. While some people experience serious reactions to treatment early on, others may be surprised to find that their symptoms during treatment are not as bad as they feared or emerge months or even years later.

Wherever you fall on this spectrum, one thing is clear: You need to pay close attention to your body and alert your healthcare team anytime something feels off, be it physical or mental. 

If you tell your treatment team about problems you are experiencing as early on as you can, they can help you find relief by prescribing medications to reduce the symptoms or changing your treatment. Treating side effects early on can also help to reduce the risk of the problems becoming more severe and potential delays in your treatment.  

One way to be sure you’ll remember to tell your healthcare team about any side effects you’re experiencing from breast cancer treatment is to track your symptoms. 

Some organizations have free worksheets available online to make symptom tracking as easy as completing a symptom checklist each day. If you prefer using your smartphone to track your symptoms, you may be able to find an app that makes this easy (just be sure you review how your information may be shared). If you don’t have the energy to print out checklists or research apps, consider simply jotting down your side effects on a piece of paper or in a journal. 

You can take this information to your appointments to make it easier to remember what you’ve experienced since your last visit.

 

Watch

Exercises to Relieve Side Effects

 

Chemotherapy works by attacking rapidly growing cells, like cancer cells. It also kills healthy, fast-growing cells. The death of your body’s healthy cells can lead to side effects like fatigue, low white blood cell counts, early menopause, and hair loss, among others. 

Learn about minimizing chemo side effects.

Hormonal therapy can block estrogen production in the body or block the effects of estrogen on breast cancer cells. Because the amount of estrogen in your body will be lower on hormonal therapy, you may experience side effects like joint and bone pain, hot flashes, fatigue, and weakness. 

Radiation therapy uses high-energy X-rays or particles to damage the DNA of cancer cells and kill them off. In the process, healthy cells may also be damaged. Radiation therapy side effects include skin peeling, fatigue, redness, and swelling, but there are other, less common side effects you may experience as well.

Immunotherapy medications boost your immune system to fight cancer cells more efficiently. These treatments can help your immune system to find and kill cancer cells. They can also lead the immune system to attack healthy cells, which can lead to inflammation. 

Targeted therapy attacks specific characteristics of cancer cells, such as a protein that allows the cancer cells to grow rapidly or abnormally. These therapies may also attack proteins that healthy cells use, leading to skin changes, fatigue, nausea, and diarrhea. 

As with any surgery, there’s a risk of infection after breast cancer surgeries like mastectomy, lumpectomy, and reconstruction. Surgery can also increase your risk of certain conditions such as lymphedema, seromas, and necrosis. You may also experience pain, including phantom breast pain after mastectomy. 

All known side effects of various breast cancer treatments can be found in the alphabetized list below. 

— Last updated on February 28, 2025 at 9:04 PM