I am a vegetarian who was diagnosed w/a b12 & d deficiency. i started getting b12 shots weekly&had an adverse reaction. how long will that last?

Whoa: If your B12 deficiency is due to being a vegetarian, you should be taking a supplement as the vegan leadership recommends. If you truly need B12 shots because you have a problem absorbing the vitamin -- and most people tolerate them fine -- you may very well have to put up with whatever's involved because otherwise you'll get permanently brain damaged. This is serious business.