Intramuscular injections can be quite painful, particularly at the injection site, and may cause mild side effects such as diarrhea, temporary itching of the skin, and a sensation of swelling
However, some people may experience mild soreness at the injection site or redness
[DOI] [PMC free article] [PubMed] [Google Scholar] 232.Weindruch R, Walford RL, Fligiel S, Guthrie D
Injections may be given to people who have malabsorption issues due to disorders such as Crohn's disease, atrophic gastritis, chronic pancreatitis, and intestinal bacterial overgrowth
If your diet is not allowing you to get enough of the B12 vitamin then a regular B12 injection regimen may be right for you
Because it is a small molecule, it is studied orally/sublingually in the literature