The anti-infective components in the combination are included to provide action against specific organisms susceptible to them. Polymyxin B sulfate and neomycin sulfate together are considered active against the following microorganisms: Staphylococcus aureus, Escherichia coli, Haemophilus influenzae, Klebsiella-Enterobacter species Neisseria species, and Pseudomonas aeruginosa. Bacitracin Zinc is highly active against gram-positive bacilli and cocci and extends the spectrum to include haemolytic streptococci, thus completing the antibacterial range of NEOCIN ointment. There is overlapping of the bactericidal spectra of these three antibiotics, thereby providing increased activity through combined antibiotic action.

Sensitization, especially to neomycin, may occur with continued or repeated use, causing redness and scaling of the treated area. Prolonged use may result in overgrowth of non-susceptible organisms. Anaphylactic reactions are rare.