Everyone knows what it feels like to be tired, fatigued, or lethargic when sick. This feeling is the most common side effect of cancer and cancer treatment. A symptom is a condition or state that something is not right in the body. Other frequent symptoms associated with cancer and cancer treatment are reduced appetite and nausea. Most patients who experience fatigue associated with cancer say that the feeling does not improve with rest, and many describe a lack of energy or exhaustion.
If fatigue arises during chemotherapy or radiation therapy, most patients experience that it will gradually go away when treatment is over and their strength is regained. This type of fatigue is considered acute. Improvement may take time depending on the intensity of treatment. Some patients experience that fatigue lasts for months, or even years. This is considered chronic fatigue. The ability to carry out daily activities, a lack of humor, health-related worries, a reduced capacity to carry out work functions, or less energy for family, can also accompany chronic fatigue. Most patients will find it difficult to be told by their doctor that they are considered healthy, while their friends and family expect them to be normal again, despite having a lack of energy and ability to perform activities they want to.
For many, feeling fatigued is often accompanied by having difficulty concentrating, poor memory, and an increased need for sleep. Most patients will need more sleep than before they became sick. For many, sleep is not restful, and it may take time to "get going" in the morning. Many also experience that they quickly become drained of strength if they exert themselves, and that it takes a long time before regaining strength after exertion. Exertion in this context can mean both physically and mentally such as working on a task that requires concentration.