The exact causes of cancer fatigue and how best to treat it aren't always clear. Find out what doctors know about cancer fatigue and what you can do about it.

By Mayo Clinic Staff

Fatigue, usually described as feeling tired, weak or exhausted, affects most people during cancer treatment. Cancer fatigue can result from the side effects of treatment or the cancer itself.

Cancer fatigue may be caused by many factors, and the factors that contribute to your cancer fatigue may be completely different from those of someone else. However, possible contributing factors include:

  • Your cancer. Your cancer can cause changes to your body that can lead to fatigue. For instance, some cancers release proteins called cytokines, which are thought to cause fatigue.

    Other cancers can increase your body's need for energy, weaken your muscles, cause damage to certain organs (such as liver, kidney, heart or lungs) or alter your body's hormones, all of which may contribute to fatigue.

  • Cancer treatment. Chemotherapy, radiation therapy, surgery, bone marrow transplantation and immunotherapy may all cause fatigue. You may experience fatigue if cancer treatment damages healthy cells in addition to the cancer cells. Or fatigue might happen as your body works to repair damage caused by treatment.

    Some treatment side effects — such as anemia, nausea, vomiting, pain, insomnia and changes in mood — also may cause fatigue.

  • Anemia. You might develop anemia if your treatment destroys too many healthy red blood cells. You can also develop anemia if the cancer has spread to your bone marrow and interferes with blood cell production or causes you to lose blood.
  • Pain. If you experience chronic pain, you may be less active, eat less, sleep less and become depressed, all of which may add to your fatigue.
  • Emotions. Anxiety, stress or depression associated with your cancer diagnosis also may lead to fatigue.
  • Lack of sleep. If you're sleeping less at night or if your sleep is frequently interrupted, you may experience fatigue.
  • Poor nutrition. In order to work efficiently, your body needs the energy that a healthy diet provides. When you have cancer, your body may need more nutrients than usual. But it can be hard to take in enough nutrients if treatment side effects, such as nausea and vomiting, make it difficult to eat.
  • Medications. Certain medications, such as pain relievers, can cause fatigue.
  • Lack of exercise. If you're used to being on the go, slowing down can make you feel fatigued.
  • Hormonal changes. Hormone therapy is a common cancer treatment that causes changes in the body's hormone levels that can lead to significant fatigue. Hormonal changes may also occur as side effects of other cancer treatments.

Not everyone who has cancer experiences fatigue. And if you do, the level of cancer fatigue you experience can vary — you may feel a mild lack of energy, or you may feel completely wiped out.

Your cancer fatigue may occur episodically and last just a short while, or it may last for several months after you complete treatment.

Some fatigue during cancer treatment is to be expected. But if you find that cancer fatigue is persistent, lasting weeks, and interferes with your ability to go about your everyday tasks, tell your doctor.

If you're fatigued, your doctor may examine you and ask you questions to assess the severity and nature of your symptoms.

Your doctor may ask:

  • When did you begin experiencing fatigue?
  • Has it progressed since your diagnosis?
  • How severe is it?
  • How long does it last?
  • What eases it?
  • What makes it worse?
  • How does it affect your daily life?
  • Do you experience shortness of breath or chest discomfort?
  • How well are you sleeping?
  • How and what are you eating?
  • How are you feeling emotionally?

Your doctor will likely conduct a physical exam and further evaluate your medical history, the type or types of treatment you are receiving or have received, and any medications you're taking. He or she may recommend tests, such as blood tests or X-rays, specific to your condition.

Because cancer-related fatigue may be caused by many factors, your doctor may suggest more than one method to reduce and cope with your symptoms. These may include self-care methods and, in certain cases, medications or medical procedures.

Medical interventions

Medications may be available to treat the underlying cause of your fatigue. For instance, if your fatigue is the result of anemia, blood transfusions may help. Medications that stimulate your bone marrow to produce more red blood cells might be another option.

If you're depressed, your doctor might suggest medications that can help reduce the depression, increase appetite and improve your sense of well-being.

Improving your ability to sleep can help relieve fatigue. Sometimes medication can be effective in helping you sleep.

Adequate pain management can go a long way in decreasing fatigue, but certain pain medications can make fatigue worse, so work with your doctor to achieve the appropriate balance.

Medications to increase alertness might be an option in certain situations.

Self-care options

Coping with fatigue might require things you can do on your own. You might try to:

  • Take it easy. Set aside time in your day to rest. Take short naps — no longer than an hour — throughout the day rather than resting for one long period.
  • Conserve your energy. Save your energy for your most important activities. Keep track of the times when you feel your best, and plan to do your important activities during those times. Ask for help when needed.
  • Maintain your energy. Drinking lots of fluids and eating well can help keep your energy reserves up. If nausea and vomiting make it hard to eat, talk to your doctor about these side effects.
  • Get moving. Moderate exercise, such as brisk walking, riding a bike and swimming, throughout the week may help you preserve your energy level. Exercise regularly as you start treatment. You'll get in the routine of exercising, and it may even help you prevent fatigue during treatment.

    If you haven't exercised much lately, check with your doctor before you begin to make sure it's safe. Then, start slow and work your way up to at least 150 minutes of exercise a week — or a half-hour of exercise on five days each week. Try to add strength training, such as lifting weights, a few times a week, too.

  • Consider integrative medicine options. Some people with cancer find relief from fatigue through meditation, yoga and other mindfulness practices that encourage relaxation. Massage and acupuncture can be helpful, too. But check with your doctor to make sure these are safe, especially if your blood counts are low or if you're taking blood thinners.
  • Ask your doctor about supplements. Supplements that contain ginseng have been shown to relieve fatigue in small studies. If you're interested in trying supplements, discuss them with your doctor, as ginseng and other supplements can interfere with medications.

Don't assume the fatigue you're experiencing is just part of the cancer experience. If it's frustrating you or affecting your ability to go about your day, it's time to talk with your doctor.

Nov. 17, 2020