Which of the following is a common side effect of radiation therapy?

Fatigue is a well-recognized and common side effect of radiation therapy. During treatment, the body's cells, including healthy cells surrounding the area being treated, can be affected. This process requires significant energy and can lead to a sense of tiredness or fatigue. Patients often report feeling more exhausted than usual, even if they are getting adequate rest. This fatigue can be exacerbated by factors such as the underlying illness being treated, the overall health of the individual, and the cumulative effect of ongoing treatments.

In contrast, increased energy levels, weight gain, and improved appetite are not typically associated with radiation therapy. These effects may not be reflective of the body’s response to treatment, as radiation is aimed at destroying cancer cells, which can lead to other systemic effects that usually cause fatigue and other symptoms.