Methyl B-12 Side Effects
Generic name: methylcobalamin
Medically reviewed by Drugs.com. Last updated on Nov 9, 2020.
Note: This document contains side effect information about methylcobalamin. Some of the dosage forms listed on this page may not apply to the brand name Methyl B-12.
Applies to methylcobalamin: injection solution, injection solution reconstituted
What are some side effects that I need to call my doctor about right away?
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:
- Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
- Shortness of breath.
- Very bad dizziness or passing out.
What are some other side effects of this drug?
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:
- Upset stomach.
- Not hungry.
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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Some side effects may not be reported. You may report them to the FDA.