One of the best acne medications is Differin. It's a topical retinoid. It is rather pricey though, but it does not have the same side effects as oral medications such as accutane.
Other things that might help are some exposure to UV light, but it natural or via a tanning bed (don't over do it). Also witch hazel is often effective and is one of the main ingredients in Pro Active solution (I think I read a consumer report once that regular OTC acne treatments (witch hazel and salicylic acid) is as effective as Pro Active, which is rather expensive.
As some others said medications like ABX or steroids that you may be on can affects your skin, so you may want to investigate that as well.