Children under age eight are usually given amoxicillin (Amoxil, Pentamox, Sumox, Trimox) because tetracycline discolors permanent teeth that have not yet come in.
Examples of penicillins are penicillin V (Beepen-VK, Pen-Vee K, V-cillin K, Veetids) and amoxicillin (Amoxil, Polymox, Trimox, Wymox).