Penicillin is one of the most commonly prescribed antibiotics. It is part of a family of antibiotics known as beta lactams, and there are many individual medications in this family: Penicillin G, nafcillin, oxacillin, cloxacillin and dicloxacillin, ampicillin, amoxicillin, carbenicillin, ticarcillin, and piperacillin. read more