Hello, The presence of hives suggests that the body is having an allergic reaction to the antibiotic. However, in some cases, it is customary not to consider the person allergic to the antibiotic, since the reaction is very minor and declaring a person allergic leads to the use of "second-line" antibiotics for the rest of their life. These second line antibiotics tend to be slightly less effective, but more toxic. For your boy, I suggest you show the hives to a pharmacist, who can judge its extent and severity, and recommend appropriate management. Have a nice day.