a method for treating side effects of anticancer agent includes administering to a subject in need thereof a prophylactic and / or therapeutic agent containing a therapeutically effective amount of a compound shown by the following formula : r 1 — nhch 2 coch 2 ch 2 coor 2 wherein r 1 represents a hydrogen atom or an acyl group , and r 2 represents a hydrogen atom , a linear or branched alkyl group , a cycloalkyl group , an aryl group , or an aralkyl group , or a salt thereof .