Along with its needing effects, a dietary supplement may cause some unwanted effects. Cyanocobalamin or hydroxocobalamin does not usually cause any side effects.
However, check with your health care professional immediately if any of the following side effects was happen
Rare soon after receiving injection only
Skin rash or itching; wheezing
Check with your health care professional as soon as possible if either of the following side effects continues or is bothersome:
Less common
Diarrhea; itching of skin
More common side effects not listed above may also occur in some individuals. If you notice any other problems, check with your health care professional.