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Updated on October 15, 2025
Fatigue is one of the most commonly reported symptoms among people with breast cancer, including metastatic breast cancer (MBC). The majority of patients with breast cancer seem to experience fatigue at some point, and fatigue is especially common among those undergoing chemotherapy.
What is fatigue?
Weary, tired, unmotivated, apathetic, drowsy, having little or no energy, and mentally exhausted are all ways that someone may feel when they are experiencing fatigue. People become fatigued for many different reasons, and it can be a normal reaction to things like physical exertion, lack of sleep, and stress.
Cancer-related fatigue is different than normal fatigue. It tends to come on faster and be more draining, it tends to be more intense and last longer, and it may significantly interfere with a person’s daily activities and quality of life.
What causes cancer-related fatigue?
There are a number of factors, both physical and psychological, that can contribute to cancer-related fatigue in people with MBC.
- Fatigue is often listed as a symptom during the initial diagnosis of breast cancer. This may be caused by an imbalance of hormones resulting from the cancer, and/or an interruption of normal biologic functions caused by the presence of cancer in the body.
- Fatigue is a commonly reported side effect for people undergoing cancer treatments, including chemotherapy, radiation therapy, and biologic therapy. Fatigue is also common for people who have undergone surgery or transplantation as part of their cancer treatment. While necessary, these treatments take a physical toll on the body, and can be mentally exhausting.
- Nausea, vomiting, loss of appetite, nutritional deficiency, and anemia are all possible side effects of cancer treatments, and can contribute to fatigue.
- Fatigue can be the result of being in pain, as well. Pain is another symptom associated with MBC, particularly breast cancer that has spread to the bones and liver.
- Fatigue is also a known side effect for certain medications used to manage pain in people with MBC and other types of cancer.
Emotional and psychological factors contribute to fatigue, too. Being diagnosed and undergoing treatment for MBC often has a profound emotional impact. Many people report anxiety, depression, and sleep disturbances, which can be both symptoms of fatigue as well as contributing factors.
Coping with fatigue
Like any other symptom or side effect, fatigue should be discussed with your healthcare provider, who can help you identify and address the underlying cause of your fatigue. Be prepared to discuss symptoms of fatigue, day-to-day habits, sleep, and how you are feeling emotionally as well as physically.
There are also steps you can take on your own to help reduce fatigue. These can include modifying your schedule to allow adequate time to rest, being willing to ask others for help when you need it, focusing on nutrition and hydration, and staying active. Exercise has numerous benefits, both physical and emotional, for people with cancer. If you’re new to exercise or unsure about what form of exercise would benefit you, talk to your healthcare provider for some guidelines on staying active.
Working to ease stress often helps to relieve fatigue, as well. Practices like mindfulness meditation and yoga can soothe anxiety and improve well-being overall. Speak to your healthcare provider for recommendations.
