What is more, the vitamin B12 forms we have discussed above do not work alone in the body, but are part of a large complex of B vitamins and operate in combination with a number of other vitamins and minerals
"Vitamin status in morbidly obese patients: a cross-sectional study"
Acta Medica Iranica
Pain and Irritation at Injection Site The most common reaction to B12 injections is pain, redness, swelling, or irritation, where the needle goes into your skin or muscle
Adverse reactions following intramuscular (IM) injection have included anxiety, mild transient diarrhea, ataxia, nervousness, pruritus, transitory exanthema, and a feeling of swelling of the entire body
Nature Communications, 11(1)