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Side Effects of Vitamin B12

Are There Side Effects to Consuming Excess Vitamin B12?

Vitamin B12 is generally safe when consumed in recommended doses. Even when the recommended dose is exceeded, it usually does not cause any noticeable side effects. This is because excess vitamin B12 does not accumulate unnecessarily in the body. Once your body absorbs as much vitamin B12 as it needs, it excretes the rest through urine.

Researchers who studied the potential side effects of this supplement in high doses for five years did not find any evidence [2] that it caused any adverse side effects. The Linus Pauling Institute [3] at Oregon State University also says that there is currently no evidence that taking doses of vitamin B12 as high as 2 milligrams orally and 1 milligram by injection causes any adverse side effects.

Still, some people report experiencing certain side effects when they use vitamin B12 supplements. These symptoms generally happen because the body has not adjusted [4] to its intake as a supplement. The symptoms typically fade within a short time, are benign, and do not require medical attention [5]. If symptoms are serious or persist, your body may not be handling the supplements well. You need to stop using it and seek medical attention. Some of the reported symptoms include: