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Methyl B-12 Side Effects

Generic name: methylcobalamin

Medically reviewed by Last updated on Nov 26, 2023.

Note: This document contains side effect information about methylcobalamin. Some dosage forms listed on this page may not apply to the brand name Methyl B-12.

Applies to methylcobalamin: injection solution, injection solution reconstituted.

Serious side effects of Methyl B-12

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

All products:


Other side effects of Methyl B-12

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:


These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

More about Methyl B-12 (methylcobalamin)

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.