I've noticed that people refer to 'Herxing' in numerous threads, stating quite categorically that this is what is happening/has happened to them. I know that this refers to the Jarisch-Herxheimer reaction resulting from release of toxins by killed pathogens. Having looked at several authoritative sites about this reaction, I am wondering how people can distinguish it from other symptoms that we get, or other things such as allergic reactions. In fact - can they? The symptoms seem quite general in nature, and most could easily have other causes or just be due to ME itself. I'm asking out of general interest in order to better understand what treatments may or may not cause it in people with ME/CFS.