Hi, I was diagnosed 3 weeks ago with B12 deficiency blood test came back 130... my doctors own words where" it's in your boots"!! and also low iron too test came back 12 for iron. I have been prescribed Cyanocobalamin 1MG tablet x 1 a day and Ferrous Sulfate 200mg 3x a day. I went to the doctors as I had been suffering with heartburn and indegestion and pain in left side of stomach and they did routine blood tests and this was the findings...I was prescribed Omerprazole for the heartburn/ Indegestion/ stomach etc which helped but still have pain in stomach so have been referred to hospital to see a gastroenterologist. Get days were I have not much energy and have definite "brain fog" and emotional for no reason just wondered if I should be on a higher dose B12? I remember at time doctor saying "I'll only prescribe X1 because of your stomache but I thought she meant iron tablets until I got my prescription and realised she obviously meant the B12... Would high doses of B12 affect your stomache?