Penicillin G (Benzylpenicillin) is an antibiotic in the Penicillin family. Penicillin G is used to treat a wide range of bacterial infections. This antibiotic is primarily active against gram-positive bacteria, which includes the acne-causing P. acnes bacterium.
Penicillin G is occasionally used in the treatment of acne, usually as a topical treatment. For oral antibiotic treatment, Penicillin V (which is closely related to Penicillin G) is much more popular than Penicillin G because it is more stable in the digestive tract.
Penicillin G and Penicillin V are notable because they consistently score very well in laboratory testing of antibiotic susceptibility of the P. acnes bacterium. These antibiotics kill P. acnes bacteria at very low concentrations, and Penicillin-resistant P. acnes bacteria are very uncommon. Clinical research and patient reports have indicated that oral treatment with Penicillin family antibiotics (eg. Amoxicillin, Ampicillin, Penicillin V) can be very effective at improving acne symptoms for many patients.
Topical Penicillin G appears to be a useful treatment for acne. Creams and ointments that contain Penicillin G are available Over The Counter (OTC) in many countries. Penicillin-containing ointments are especially popular in Central and South America. Several of these ointments combine Penicillin G with a complementary antibiotic from a different antibiotic family (eg. Sulfonamide).
Clinical research on the use of these Penicillin G combination ointments for acne treatment is currently limited. But patient reports and laboratory antibiotic susceptibility testing both suggest that some of these combination ointments (eg. Penicillin plus Sulfathiazole) may be uniquely effective acne treatments. More research is needed, but this subset of topical antibiotic treatments clearly warrants greater interest from the acne community.