They result when normal cells that are damaged by radiation aimed at cancer cells. Side effects can be acute, mild, and temporary, or they can be more serious and permanent. Normal cells that are rapidly growing or regenerating are more prone to side effects. Examples are bone marrow, intestines, hair follicles, the lenses of the eyes, kidneys, liver, and lungs. The brain, heart, cartilage, and bone are less sensitive.
Some side effects are acute, but go away on their own.
These include hair loss, skin burn, nausea, fatigue, mouth sores, diarrhea, and drops in blood cell counts. Other side effects can develop more slowly and are permanent. These include necrosis or death of bone, and pneumonitis, an irritation of the lungs. Later side effects also include fibrosis, loss of skin blood vessels, intestinal damage, and bowel obstruction. Organ failure, such as the loss of kidney or heart function, may also occur.