I'm very sensitive to lots of meds. I can't take steroids, because I have Avascular Necrosis. I'm very sensitive to any opioid. The one time that I tried Tramadol was a day-long disaster. I'm so allergic to opioids, I can't even eat something with poppy seeds in it.
The few times that I've been anesthetized, I take longer to come out of it than most people, and I get extremely sick. Most pain meds knock me out. Baclofen helps a bit with muscle spasms, but a whole pill will make me sleep for 14 hrs. straight and still be groggy afterward. My hubby cuts them in half for me if I'm spasming badly enough to take one.
I'm a real mess when it comes to meds!
As for caffeine - if I ever had to give up my daily coffee, life wouldn't be worth living! I'm also a chocoholic, so it's a good thing that I can handle caffeine!