A common external-radiation side effect includes which symptom?

• A. Hair loss
• B. Mucositis
• C. Constipation
• D. Headache

Answer: (A)

External radiation therapy affects cells that divide quickly within the area being treated. Hair follicles fall into this category, so hair loss in the treated region is a common and expected side effect. It often appears after a few weeks of treatment and can be temporary, with hair regrowth after therapy ends (though higher doses can cause longer-lasting or permanent shedding in the treated area). Other options don’t fit as neatly: mucositis involves mucous membranes (more likely with head/neck radiation or chemoradiation), constipation is not a typical direct radiation effect, and headaches are not specifically linked to the radiation field. Thus, hair loss is the most characteristic external-radiation side effect.