I originally started taking B12 shots to correct a diagnosed difficiency. As discribed by others, I developed a bad acne-type rash, which no-one could explain. When I finally linked it to the B12, and stopped the injections, it seemed like a long time before it cleared up.
I have tried taking 1000mg in the oral form several times since, but always end up with the acne-type side effect.
To date, I have found no solution to my dilema, but I see that I am not alone!