I agree with what Sherlock said.. dysautonomia thou it causes sooo many of the ME/CFS symptoms eg IBS, headaches, tiredness, etc.. things like abnormal immune stuff can help one to tell one dont "just" have dysautonomia.. eg swollen glands, sore throats help point to ME. Thou I do have very bad dysautonomina.. its obvious I have more then that due to all the rest of the symptoms I get... in my case my white blood cells are only just within normal range and never really raise (many ME/CFS specialists would say that points to chronic infection). I also have a history of severe EBV (also did have FM at the start of my ME). I also have abnormally low cortisol etc.. a lot of things which point to me having more then just dysautonomia. Developing many food intollerances would point to ME. Dysautonomia thou can cause some PEM as sometimes the effects of blood not getting to the brain enough can end up leaving one with after affects depending on how bad the dysautonomia was affecting one at the time (thou yeah usually recovering from a dysautonomia crash is far faster then ME crash recovery). Im not sure if one could use alcohol intollerance to help distinguish between those who just have dysautonomia and those who have ME and dysautonomia.. as I think many people who just have dysautonomia have issues with alcohol too. (does alcohol affect the autonomic system?) Without dysautonomia testing, I dont think most doctors would be able to tell a severe dysautonomia case with that alone.. apart from ME/CFS .. its the kind of thing only a good specialist with good understanding of dysautonomia could distinguish. .. There would be many people in the ME/CFS communities with a CFS diagnoses which in fact ONLY have dysautonomia which has gone undiagnosed (which is a real pity as many of those people otherwise may be able to be being treated and doing much better). Same wrong diagnosing goes with FM..some with only FM have been wrongly given a ME/CFS diagnoses due to so much overlap in the symptoms eg FM people are more prone to migraines, IBS, sleep issues, fibro fog and fatigue... If someone lives in England and has both dysautonomia and ME.. probably would be a good idea to get focus on the dysautonomia causing most of your symptoms as far as diagnoses goes and try to get the ME/CFS diagnoses wiped so you get treated better by doctors.