Unlike some chemotherapy drugs that pass through the bloodstream and reach all the body parts (including the scalp), radiotherapy does not have a general toxic action on the hair follicles will not cause hair loss. However, in patients undergoingbrain irradiation, hair loss may be observed in patches in the area where the radiation beam passes. It occurs 2 to 3 weeks after treatment initiation and the hair will usually grow back within few weeks. In patients undergoing whole brain irradiation, hair loss will concern the entire scalp.
