I've noticed since my CFS has gotten bad, my ability to tolerate medicines and even supplements is awful. I've had some pretty bad reactions including a very bad antibiotic reaction tonight that was quite scary. I'm scared that the infection I have will end up needing one of the antibiotics I've had a reaction to in order to be cured, then what will I do? So far one antibiotic I can tolerate has not worked on the infection and there are several I've had reactions to in the past so they have not tried them on me this time. I'm the same way with most sleep meds, with antidepressant (that doctors are always trying to give for every kind of problem, never depression in my case) and other medicines. I notice with supplements that if I take one, right away I end up having symptoms of low levels of some other vitamin that competes with the one I'm taking, so I've mostly just given up on them all except for a multivitamin. Even vitamin D I have major problems with. How do others deal with this issue if you have it? It's hard not being able to tolerate meds and reacting to everything, especially when it's less of an optional thing and you really just have to have medicine, like when you have an infection. Also, some people here mention oxidative stress and gluthatione (spelling?) a lot (I admit I still don't understand and have no clue what these things are). Based on what I read after my bad medicine reaction tonight, I see that some med reaction can be related to that so I wonder if having CFS, that has something to do with how I react to some meds? ETA: I also saw electrolyte issues or low B vitamins can affect some antibiotic reactions. I'm not sure if these may also be CFS related issues I might have. It's also a shame doctors mostly know nothing about CFS and how debilitating it is so they rarely seem to understand that the things they think are fine and will have no side effects may not be that way for a person whose body is already under severe phsycial stress and CFS related problems.