Why can rh plus blood be given only once to a non sensitized person who is rh?

Rh-positive blood can be given to a non-sensitized person who is Rh-negative only once because the recipient's immune system may not have previously encountered Rh-positive antigens. If the recipient is exposed to Rh-positive blood again, their immune system could recognize the Rh antigens as foreign and mount an immune response, leading to hemolytic reactions. This risk underscores the importance of blood compatibility in transfusions to avoid potential complications.