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Feeling Tired vs. Cancer-Related Fatigue

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

Cancer-related fatigue is different

Research suggests that most people getting cancer treatment have fatigue. Cancer-related fatigue is very different from everyday fatigue. Cancer-related fatigue is worse. It lasts longer and sleep doesn’t make it better: it’s unpredictable.

Many people describe it as overwhelming, affecting every part of their lives. It leaves them feeling physically, mentally, and emotionally exhausted.

For patients getting chemotherapy in cycles, fatigue often gets worse in the first 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.

Cancer-related fatigue can last from months to years after treatment ends, too. Many people with cancer say fatigue is the most distressing side effect of cancer and its treatment.

Left untreated, cancer-related fatigue can upset the patient’s quality of life. It can affect daily routines, self-care, recreation, and relationships.

Some signs of cancer-related fatigue are:

  • Prolonged, extreme tiredness after exertion
  • Feeling weak, tired, weary, or exhausted even after sleeping
  • Arms and legs may feel heavy and hard to move
  • Trouble completing your daily activities due to fatigue
  • Having trouble concentrating, thinking clearly, or remembering
  • Feeling frustrated, irritable, and upset about the tiredness and its effects
  • Not taking part in normal day-to-day activities
  • Putting less energy into personal appearance
  • Spending more time in bed or sleeping

Causes of cancer-related fatigue

The causes of cancer-related fatigue are not fully known. It may be caused by the cancer and/or the cancer treatment. Problems like low blood counts, sleep problems, stress, pain, eating too little, lack of exercise, and other factors are also thought to be linked to this kind of fatigue.

It’s important for you to tell your doctors about any unpleasant effects you’re having. This way your health care team can monitor and treat those problems, both during 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 might want to run tests to check for hidden medical problems. Medical causes can sometimes be found and treated. If no treatable medical cause is found, there are practical ways to manage and minimize cancer-related fatigue, including good sleep habits, approved physical activities, and smart use of your time and energy. Doctors are also researching medicines to help people manage fatigue.

Be sure you talk to someone on your health care team if you think you may have cancer-related fatigue. You may need to come up with different ways to do things, decide what you can give up, set priorities, and get help so you can better manage it.

Fatigue or depression?

Some signs of fatigue look a lot like those of depression, and it’s easy to confuse them. Depression involves an inability to feel pleasure – people who are depressed feel sad or unworthy, and have despair or guilt. You can have fatigue and not be depressed, although some people have both fatigue and depression.

Sometimes it may be hard to find a label for what you’re feeling. Even your doctor may want you see a mental health professional to get another opinion on whether depression is part of the problem. If it is, treatment can help.

Try to tell your doctor exactly how you feel and how it affects the things you do. People with fatigue may describe feeling tired, weak, exhausted, weary, worn-out, or slow. They often have no energy and cannot focus. They may feel sad, irritable, or frustrated.

Only you know if you have fatigue and how it’s changing your ability to enjoy life. Talk to your health care team so you can find ways to feel better.

To learn more

7 Ways to Manage Cancer-Related Fatigue

Fatigue in People With Cancer

Anxiety, Fear, and Depression

Distress in People With Cancer


Jacobsen PB, Donovan KA, Weitzner MA. Distinguishing fatigue and depression in patients with cancer. Semin Clin Neuropsychiatry. 2003;8(4):229-240.

National Cancer Institute. Fatigue (PDQ®). Accessed at www.cancer.gov/cancertopics/pdq/supportivecare/fatigue/HealthProfessional on September 26, 2013.

Trudel-Fitzgerald C, Savard J, Ivers H. Which symptoms come first? Exploration of temporal relationships between cancer-related symptoms over an 18-month period. Ann Behav Med. 2013;45(3):329-337.

Mitchell SA, Berger AM. Fatigue. In Cancer: Principles & Practice of Oncology, 9th Ed. DeVita VT Jr, Lawrence TS, Rosenberg SA (Eds). Philadelphia, Lippincott, Williams & Wilkins. 2011: 2387-2392.

Last Medical Review: 10/07/2013
Last Revised: 10/07/2013