It also plays a role in how your body creates energy
Efficacy of supplementation with methylcobalamin and cyancobalamin in maintaining the level of serum holotranscobalamin in a group of plantbased diet (vegan) adults. Experimental and Therapeutic Medicine 22(3) (2021): 17
We do not recommend B12 injections for anyone pregnant or nursing
Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect: Signs of an allergic reaction, like skin rash, hives with itching and red swollen blistered peeling skin with or without fever, wheezing, tightness in the chest or throat, trouble breathing, trouble swallowing, trouble talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat