If you are fighting cancer, chances are you're also fighting fatigue. Fatigue is the most common side effect of cancer treatment, and it often hits without warning. Everyday activities -- talking on the telephone, shopping for groceries, even lifting a fork to eat -- can become daunting tasks.

Cancer-related fatigue is different

Cancer-related fatigue feels very different from everyday fatigue, said Lillian Nail, PhD, RN, a cancer survivor who has studied this side effect at the University of Utah School of Nursing.

"'Overwhelming' is the most common description," said Dr. Nail. "When compared with the fatigue experienced by healthy people, cancer-related fatigue is more severe, it lasts longer, and sleep just doesn't bring relief." The causes of cancer-related fatigue are not fully known. Problems like low blood counts, sleep problems, stress, eating too little, lack of exercise, and other factors may be linked to this type of fatigue.

A common, frustrating problem

About 90% of patients have fatigue during chemotherapy or radiation therapy treatment, added Dr. Nail. For patients getting chemotherapy in cycles, fatigue often peaks within a few days and then gets better until the next treatment when the pattern begins again. For patients getting radiation, fatigue usually gets worse as the treatment goes on.

Fatigue may last from 3 months to a year after treatment ends. And it may last even longer for patients who had bone marrow transplants. For these patients, their personal definition of what is normal changes; being tired becomes the new normal, said Barbara Piper, DNSc, RN, associate professor of nursing at the University of Nebraska.

Mental fatigue often results from the intense mental effort and attention that is part of coping with a serious illness. "For example, a woman with newly diagnosed breast cancer must absorb the impact of the diagnosis as well as make treatment decisions to go on with her life," added Piper. Doctors often don't prepare patients for this frustrating side-effect of cancer, said Russell Portenoy, MD, chairman of the Department of Pain Medicine and Palliative Care at Beth Israel Medical Center in New York City, and a member of the Fatigue Coalition, a group of medical researchers and practitioners who are making more patients and health care providers aware of this condition. Left untreated, fatigue can upset the patient’s quality of life.

Is it fatigue or depression?

Because some fatigue symptoms look a lot like those of depression, health care providers often confuse the two, said Dr. Nail. Depression involves an inability to feel pleasure -- people who are depressed feel sad, unworthy, despair or guilt. "It's entirely possible to be fatigued but not depressed," she explained, adding that patients sometimes have trouble finding a label for what they’re feeling. They just know they can be overwhelmed with fatigue at any time, no matter what they are doing.

What are some signs of cancer-related fatigue?

• feeling tired, weary or exhausted even after sleeping
• lacking energy to do your regular activities
• having trouble concentrating, thinking clearly, or remembering
• feeling negative, irritable, impatient, or unmotivated
• lacking interest in normal day-to-day activities
• spending less attention on personal appearance
• spending more time in bed or sleeping

What causes cancer-related fatigue?

At times, there may be physical causes of fatigue, like infection or pain that disrupts sleep. It's important that people talk to their doctors about any unpleasant side-effects they are having. This way the health care team can monitor and treat those problems, both during active cancer treatment and afterward when some physical problems can linger.

When there are no obvious physical causes for a patient or survivor's excessive fatigue, doctors may want to run tests to rule out hidden medical problems. When medical issues are ruled out, certain practical methods have been developed to manage and minimize cancer-related fatigue, including good "sleep hygiene," approved physical activities, and smart use of your time and energy. Dr. Nail added, "It's a matter of identifying the times of day when you have more energy than others," she explained. "It means finding alternative ways of doing things, deciding what you can give up, setting priorities, and then getting help."

Additional resources

• 7 Ways to Manage Cancer-Related Fatigue (Severe Tiredness)

• Fatigue in People With Cancer

Last Medical Review: 10/08/2008
Last Revised: 10/08/2008