Vitamin B12 (cobalamin) is a water-soluble vitamin that is necessary for red blood cell formation, brain function and DNA synthesis. B12 deficiency can lead to anemia and brain disorders from nerve damage. According to the National Institutes of Health (NIH), vitamin B12 injections are used to treat severe deficiencies caused by pernicious anemia, diseases, malabsorption, infections and interactions with certain medications.
Common Problems
Common side effects of B12 supplementation, according to the Mayo Clinic and the NIH, are diarrhea, itching and a feeling of being swollen.
Rare Problems
Rare problems reported with vitamin B12 supplements include rash, hives and wheezing, which the Mayo Clinic says can occur up to four months after supplementation has been discontinued. Rosacea fulminans has also been associated with B12 supplements. It is a condition that causes facial flushing and skin changes that resemble acne. The Mayo Clinic also mentions peripheral vascular thrombosis as a reported side effect that causes arterial blockages in the arms and legs which can lead to pain, numbness and ulcers in the limbs.
Additional Problems
Additional rare but reported side effects according to the NIH include muscle weakness, cramps and pain, excessive thirst and urination, confusion, shortness of breath, fatigue, headache, dizziness and difficulty breathing or swallowing.
About this Author
Bethany Fong is a registered dietitian and chef from Honolulu, Hawaii. She has produced a variety of health education materials on multiple topics relating to wellness, and worked in many industries, including clinical dietetics, food service management and public health.
