A penicillin injection, such as the antibiotic medication called Bicillin, can be quite painful, especially for children. This is an intra-muscular injection that is prescribed for many types of bacterial infections, including strep throat, syphilis and yaws, relates WebMD. The medication also can be administered to prevent the growth of bacteria associated with rheumatic fever.
Bicillin is only one of many injectable penicillin medications available. Some others are temocillin and benzylpenicillin. Injectable penicillin, which is a long-acting medication, needs to be injected into a large muscle found in an area like the thighs. The dosage can be dependent on factors like the specific condition and weight in the case of children, reports WebMD.