b12 injection side effects pregnancy vitamin injections in safety The of supplementation and postpartum on growth and neurodevelopment Compounded Cyanocobalamin (Vitamin B12) Injection

In rare situations, B12 shots itching rash anaphylaxis, a life threatening condition that can cause a fast heartbeat and difficulty breathing Other side effects that can occur include: shortness of breath, fast weight gain, and swelling congestive heart failure, the inability of the heart to adequately pump blood pulmonary edema, the buildup of fluid in the lungs peripheral vascular thrombosis, the obstruction of a vein with a blood clot hypokalemia, low potassium levels that can cause irregular heartbeats and muscle weakness fever tingling, numbness, and joint pain swollen tongue polycythemia, an increase in the red blood cell mass Additionally, B12 B12 shots are not necessary for weight loss

National Academies Press (US).

PMID 27886704

The disulfide bridge between Cys and Cys is essential for maintaining the peptides bioactive conformation