Important Safety Information: B12

Injections may cause injection-site pain, redness, or swelling. Less commonly, diarrhea, itching, or allergic reaction. MIC components are reviewed against kidney and liver function. Correcting a significant B12 deficiency can lower potassium sharply enough to require monitoring and replacement in the first 48 hours. FDA labeling for cyanocobalamin injection links this to a risk of sudden death in severe, intensely treated megaloblastic anemia.