I found out I have low b12 a few months ago after months of fighting with the doctors and being told I was fine. I had the loading dose then I'm supposed to have them 12 weekly now but a few weeks ago about 6 weeks after the loading dose my symptoms started creeping back so I visited the doctor but was told under no circumstances could I have it earlier than 12 weeks as it would overload me, now I'm back to square 1..falling asleep all the time, muscle weakness etc some days I barely have the energy to look after my 13 month old dd! Does anybody have any experience of low b12 and is the doctor right in saying I can't have it early? I'm sure the nurse told me if 12 weeks was too long I could have it earlier. I'm exhausted :(