What Is Cancer-related Fatigue?
Many people with cancer have fatigue (a feeling of being very tired, low-energy, and worn out). You might have cancer-related fatigue before, during, and after treatment. Some people with cancer report that their fatigue lasts for weeks, months, or even years after they finish treatment.
Cancer-related fatigue
Cancer-related fatigue (CRF) is a physical, emotional, and mental feeling of tiredness or exhaustion in someone with cancer. This feeling doesn’t get better with rest and sleep.
CRF is often worse and harder to manage than the fatigue people who don’t have cancer get. It can happen whether or not you are in cancer treatment.
What causes cancer-related fatigue?
Cancer-related fatigue (CRF) can be a symptom of cancer itself. This is especially true if your cancer is more advanced. But there are also many other things that can cause CRF.
This includes:
Certain cancer treatments
Certain cancer treatments can cause fatigue. For example:
- Chemotherapy. Fatigue starts in the days after a chemotherapy treatment and usually gets better before your next treatment.
- Radiation therapy. Fatigue often starts a few weeks after beginning radiation therapy and is at its worst near the end of treatment. It then gets better over the next weeks and months.
- Immunotherapy. Fatigue most often starts in the first few weeks to months of immunotherapy. But it can happen at any time during your treatment, depending on the type of immunotherapy you get.
- Surgery. Fatigue starts right after surgery and gets better as you heal.
Anemia
Certain treatments, like chemotherapy, radiation therapy, and surgery can cause the number of red blood cells in your body to go down. When this happens, it’s called anemia. Anemia can cause fatigue.
Pain
Living with pain can wear you out and make you feel tired. Many pain medicines can also cause drowsiness and fatigue.
Distress, anxiety, and depression
Strong emotions, moods or mental health issues can cause or make fatigue worse. Fatigue may also make these emotions stronger.
Sleep problems
Many people with cancer have insomnia (trouble falling asleep or staying asleep). Not getting enough sleep, or good quality sleep, can make you feel more tired during the day.
Other problems such as sleep apnea and restless leg syndrome can also prevent you from sleeping well.
Sleep apnea is rarely caused by cancer or cancer treatment. It is usually something a person has before they are diagnosed with cancer. Like sleep apnea, restless leg syndrome can happen to people who don’t have cancer. But some people get it during chemotherapy.
Problems eating and drinking
A well-balanced diet and plenty of liquids can help reduce fatigue. But people with cancer often have problems getting enough to eat and drink because of:
- Loss of appetite
- Nausea and vomiting
- Mouth sores and pain
- Mouth dryness or thick saliva
- Trouble swallowing
- Taste and smell changes
Not getting enough physical activity
Too much time spent resting or sitting can lead to fatigue, loss of body function, and muscle weakness.
Medicines
Some medicines can make you feel sleeper and more tired. Pain medicines, antihistamines, and medicines to help you relax or sleep are the ones most likely to worsen fatigue.
Other health conditions
You might have other health conditions that make your cancer-related fatigue worse. This is especially true if you are older. Other health conditions that can worsen fatigue include: arthritis, heart or breathing problems, and hormone problems.
Symptoms of fatigue
People with cancer-related fatigue often describe feeling very tired, weak, exhausted, weary, or worn-out. Fatigue can make it hard for you to keep up with your work, social life, or daily routine. For some people with cancer, fatigue can cause even more distress than side effects like pain, nausea, or vomiting.
Cancer-related fatigue might make you feel:
- Tired in a way that doesn’t get better with rest or sleep
- More tired than usual during or after an activity
- Too tired to do the things you normally do
- Like your arms and legs are heavy and hard to move
- Like you have no energy
- Sad, cranky, or frustrated
- Very weak
- Like you can’t concentrate or focus your thoughts
- Like you need more sleep (or you might have trouble sleeping)
Your fatigue can be different from one day to the next. Some days it might be worse or bother you more. Cancer-related fatigue may take weeks or months to totally resolve, but it gets better over time.
Is it fatigue or weakness?
Fatigue and weakness are often used to describe the same thing, but they are not the same. Fatigue means having a lack of energy. Weakness means feeling like you have less muscle strength. Both fatigue and weakness make it harder to do your usual activities, but for different reasons.
Is it fatigue or depression?
Some symptoms of fatigue might seem a lot like symptoms of depression. You can have fatigue and not be depressed, but some people have both.
Talk with your doctor or cancer care team if you have symptoms that seem like depression or fatigue. They may want you to see a mental health provider to figure out if depression is part of the problem. If it is, treatment might help.
Learn more about managing cancer-related fatigue.
- Written by
- References
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.
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Last Revised: July 16, 2024
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