can b12 injections cause fever Signs You May Have a Deficiency Vitamin B12: The Hidden Danger

Too much vitamin B12 intake can cause headache, nausea and vomiting, diarrhea, fatigue, weakness, and tingling

Reduction in the activity of this enzyme decreases the conversion of substrates into fatty acids, thereby shifting cellular metabolism toward lipid mobilization rather than storage [1]

Formulations of cyanocobalamin injection containing benzyl alcohol as a preservative should also be avoided in premature neonates and those with hypersensitivity due to its association with gasping syndrome (10-12)

[19] [21] Ascorbic acid, the sole active ingredient in this injection, exerts its physiological effects primarily through its role as a potent antioxidant and enzymatic cofactor

This represents a significant gap between regulatory approval for safety (as a food substance) and clinical efficacy (which is absent or insufficient for weight loss)