I don't think I'm as immune to medicine as you are BUT.... very few work on me. I posted a long time ago that the only two drugs that actually work on me are Alka-Seltzer and Metamucil. That's a bit of hyperbole but not much... I stand by it.

I have never taken a dose of cough medicine that did squat. Prescription or otherwise. No headache remedy has ever relieved my headache in the least.... but admittedly I very seldom get headaches. Pain medications do not relieve my pain... although a couple of them while not relieving my pain do make me not give a hoot that I'm in pain.