What do you suggest if my child is 11& has developed acne, doctor has prescribed purbac. i want to know how safe is this medican?

Consider 2nd Dr: Purbac is a combination antibiotic; a systemic tetracycline is probably a better choice if a systemic antibiotic is required at all, and an antibiotic must never be used as sole Rx for acne. It's important Junior be acne-free in the challenging years ahead; topical benzoyl peroxide should probably start now and you should consider a dermatology consult.