Hi All - I'm having ongoing investigations for what feels like chronic fatigue syndrome and looks like it may be some sort of auto-immune syndrome. I've been ill for a year, had loading doses back last March, which felt miraculous and completely brought be back to "normal", then I slowly drifted back to baseline (feeling awful) over a few months, began SI -- because of course! it was B12 that had brought me back to life! I was SI every other day in a completely futile attempt to get that first lift back -- it never came. Have now been to a private diagnostician/specialist and investigations are still ongoing, but I believe now that although I may have had a B12 issue, and B12 may be part of the syndrome I have (i'm fine for ferritin, folate, IF negative, though I know not reliable), I believe now I was too convinced that B12 was the one answer. Despite the fact that months of SI made no difference to my health, I was caught up in a cycle of certainty that THIS was my problem. This is not remotely to denigrate the people that B12 is helping/saving, and I know there are many. Just wanted to say to keep your mind open, and understand that there may be bigger/other/separate health issues causing your symptoms. I'll report back when I have a definite answer to mine.