Sudafed (Pseudoephedrine HCL) is basically a mild stimulant. This is what illegal drug producers make crystal meth from. I use Sudafed (actually any store chain generic) on occaision when I am having a bad focusing day.
I don't think it is bad to take to help with your focus, it's dirt cheap compared to Ritalin, Concerta, Adderal, etc. I'll venture to say that it is safer than the prescription stimulants. Medical professionals know this but the prescription drug industry controls them. $$$$$$$