Do you think it would be reasonable to add "herx" to your list of abbreviations? (Maybe you could add it and say "see below" or something.) I know I didn't know what it meant at first, and figured someone would explain it sooner or later. Then someone asked, and madwolf (of course) explained it. Let me first say thank you for making the list and updating it! If you think so, here it is: Herxheimer Reaction (Herx) The Herx is that flu like feeling that some of us get when we take antibiotics to kill off the little critters (mycoplasma, chlamydia, various virii) that infect us and cause FM/CFIDS. As they die off, they release into the blood stream (ours) toxins that cause us to fell like he**. These critters do not do well in an oxytgen rich environment. Some of us are using oxygen therapy to fight them along with the antibiotics. The question, then, is whether the oxygen rich environment created by the deep breathing we do when we exercise kills of those critters which then release their toxins, giving us that flu-like feeling (Herx) that most of us get after exercise.