Cancer fatigue is when you feel very weak and exhausted during cancer treatment. You may struggle to complete daily tasks. Fatigue can last for weeks or even years.

Chemotherapy Through Cardiovascular System
Chemotherapy
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Cancer and the side effects of treatment cause this condition. If your body is already weakened by cancer when treatment begins, then it is even more difficult to handle the side effects.

These conditions are caused by cancer or cancer treatment and can add to fatigue:

  • Anemia—due to chemotherapy, which can kill red blood cells and affect the blood-forming cells in bone marrow
  • Poor nutrition and dehydration—due to loss of appetite, nausea, and vomiting
  • Lack of oxygen—due to fewer red blood cells, which carry oxygen
  • Hormonal changes—due to hormonal therapies, side effects of treatment, or type of cancer, such as thyroid cancer
  • Other factors:
    • Lack of sleep
    • Depression
    • Stress
    • Pain
    • Side effects of medicines