I too broke out in spots when I was given B12 injections. The spots were initially mis-diagnosed as folliculitis and I was on antibiotics for months - which had absolutely no effect on the spots The spots were mainly on my face, scalp, neck, chest and seemed only to appear on my upper body. They appeared at first to be little itchy spots which then turned red and pustular (like acne) after a few days - taking a long time to go away. New spots kept appearing months after I had had the initial shots. I have since had similar outbreaks each time I have the injections but I have reduced the dosage and the spots are not as bad and I still get quite itchy. Not sure what the solution is other than maybe trying the other forms of B12 which can be taken orally?