A deficiency is typically treated with B12 supplements or intramuscular injections for several months or more. These treatments may contain methylcobalamin, but cyanocobalamin is more commonly used.
Adverse drug reactions observed in the mecobalamin 50 mg group were constipation, injection site pain, fever, electrocardiogram QT prolongation, and rash, occurring in 1.5% (1/65 cases) each.2 (1) Oki ...