Vitamin B12

Common known side effects

Along with its needed effects, a dietary supplement may cause some unwanted effects. Vitamin B12 does not usually cause any side effects.

Check with your doctor immediately if any of the following side effects occur:

Rare

soon after receiving injection only

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.