Guess what happens when people take antihistamines... Lovely, lovely side effects. Side effects which are generally equally as annoying as the original problem.

If one can treat the symptoms just as easily as the cause and pseudoephedrine doesn't make them feel like a drugged-out zombie, just guess which drug people are going to take...

...and yes, doctors actually will write prescriptions for pseudoephidrine because they're generally pretty sure their patients aren't using it to make meth. I know three people who've gotten such prescriptions, and I've been tempted to do the same thing myself.