Erythromycin ointment is an over-the-counter drug in the category of dermatologic drugs. It is used for impetigo and other suppurative skin and small area burns, ulcer surface infections and common acne. It is a macrolide antibiotic, has antibacterial activity against most gram-positive bacteria, some gram-negative bacteria and some atypical bacteria such as chlamydia, mycoplasma. It is suitable for: 1. trachoma, conjunctivitis, keratitis. 2. prevention of neonatal gonococcal and Chlamydia trachomatis eye infections, in the case of not severe infection can also be used erythromycin ophthalmic ointment for the treatment of infection of the pubic area, and the effect is very significant. Erythromycin is a macrolide antibiotic, the mechanism of action is to inhibit the synthesis of bacterial proteins, gram-positive bacteria and Chlamydia trachomatis have antibacterial effect. Bactrim acts on the isoleucine tRNA synthetase and isoleucine binding site in the bacterial body, hindering the synthesis of amino acids, and at the same time depletes the intracellular tRNA, so that the RNA and protein synthesis of the sensitive bacteria is suspended. Pepto-Bismol is a topical antibiotic for a variety of bacterial skin infections, such as pustules, boils and folliculitis and other primary skin infections, as well as eczema co-infections, ulcers co-infections, trauma co-infections and other secondary infections. So, it can be said that these two creams are anti-inflammatory effect, but this does not mean that the two can be used interchangeably.