This page was reviewed under our medical and editorial policy by
Maurie Markman, MD, President, Medicine & Science
This page was updated on April 29, 2022.
With cancer, you may feel worn down and weak at times. You may not always have the energy to do the things you love—like spending time with family and friends. Some days, you may not think clearly or remember things. You may sleep a lot, but it doesn’t get better.
You’re not alone. Fatigue is common among cancer patients. The cancer itself or treatment may cause it.
In fact, most cancer patients experience fatigue at some point.
Cancer-related fatigue isn’t the same as what you may have felt before your diagnosis. It’s more than just feeling tired, and it doesn’t go away when you get enough sleep or rest. Fatigue feels different to each patient, but it’s extreme and persistent—and it often gets in the way of doing things you want or need to do.
Fatigue may travel with other symptoms, such as pain, breathing problems, anemia, emotional distress and sleep issues. It may last from weeks to years, and it may get better or worse at different points in your treatment and cancer journey.
Both the physical and mental effects of this fatigue, along with the stressors that come from it, may challenge your quality of life.
Different factors may cause fatigue, such as:
You may also feel fatigue if you have nutritional challenges, such as:
Chemotherapy, radiation therapy, immunotherapy, targeted therapy and surgery may cause fatigue, too.
The fatigue you experience while undergoing cancer-fighting treatment may be different throughout its entirety. For example, you may feel more fatigued right after getting chemotherapy treatment, and it may worsen over the course of your treatment but go away once it’s completed.
If you’re older, are on more than one type of treatment, or have more advanced cancer, you may be more likely to experience long-term fatigue.
It’s important to tell your family and care team if you’re experiencing fatigue.
There’s no test to diagnose it, but your doctor may ask questions, examine your body and may order a blood test to look for causes and solutions.
When experiencing fatigue, it’s helpful to keep a log of:
Keeping a journal of your symptoms may come in handy when you connect with your care team.
Though fatigue usually lessens or goes away after treatment, for many patients, it lingers. Many advanced cancer patients who aren’t receiving treatment experience fatigue, too.
What your doctor suggests to address your fatigue may be different after treatment. So, be sure to speak with your care team regularly about fatigue and any changes that may affect how it’s managed.
During this discussion, your doctor may recommend:
If you’re having trouble paying attention, thinking clearly, remembering or understanding, take time to sleep. Restful activities and time outdoors may help, in particular.
Researchers are also studying the possible effectiveness of other treatments, integrative support therapies and dietary supplements that may help with fatigue.
Though it may seem especially hard to do when you have so little energy, moderate exercise or activity may help lessen cancer-related fatigue.
Research shows that exercise is safe for cancer patients in general—with your doctor’s OK.
Make sure you speak with your doctor before starting or changing your exercise program or activity levels. A physical therapist or other exercise specialist may be able to help you develop a plan.
Cancer and its treatment may change the way your body absorbs and uses food for energy. It may also cause appetite loss, nausea, vomiting or diarrhea that make it hard for you to get enough nutrients from food. This may all cause fatigue.
Eating calorie- and protein-rich foods may help. Eating small snacks throughout the day, instead of large meals, may help keep your energy up. This is especially helpful if you don’t have a large appetite or if you get full fast.
Staying hydrated is also important. Limit caffeine and alcohol, and sip on non-caffeinated fluids throughout the day.
Registered dietitians have training in identifying foods that may increase your energy—as well as those that may zap it. They’re able to develop a nutritional plan that targets fatigue and other challenges you may be experiencing.
You may need to decide what’s most important to you and prioritize those activities. Ask for help getting other necessary tasks done, and let your family and friends know if you just don’t have the energy to do something.
Tell your care team whenever you’re experiencing cancer symptoms or side effects from treatment, including fatigue. They may be able to suggest strategies or treatments that may help you feel better.
Remember: Your team won’t be able to help you if they don’t know you’re experiencing problems. Keep track of the things that are affecting your quality of life and discuss them with your care team.