what are the consequences, if any, of vitamin b12 overdose?

Factual Questions
1

anyone know?

2

Google does. :smiley:

http://www.mayhospi.com/Vitamins/nd-vitaminB12.asp

3

As DDG showed in her links, chances of lethal toxicity are nil. But to much B12 in injection can lead to a similar agitated state as with too much caffiene.

Link.