Acne outbreaks caused by the build up of harmful bacteria on the skin is always better to treat with antibiotics. Noeosporin contains polymyxn b, bacitracin and neomycin -it's more effective.
Although Neosporin has antibacterial properties, it is not a good acne medication as it can clog pores; try using a cream that states it is specifically made for ance.
Neosporin is not advertised as a cure for pimples however it can be used to treat the blemishes due to pimples. It should also be used if a pimple has popped or an infection had led to a discoloration.
I have never tried Neosporin for pimples. It is used to help heal wounds so I don't think it would hurt to try. There are many acne medications on the market but I have never seen this listed as one.