Not having enough can cause tiredness, brain issues, and big red blood cells
This makes it an excellent option for post-operative care, helping to shorten recovery time and manage discomfort
10.1007/s12264-018-0269-8 151 WhittleB
The B12 deficiency itself getting worse, either because not enough unhealthy red blood cells have expired and been replaced by healthy ones (each one of them has a 90 day life-cycle), or because the B12 wasnt injected on a daily schedule
Side effects are usually mild, like redness or tenderness at the injection site, and they disappear quickly
For the nasal route, reconstitute with BAC water containing NaCl rather than plain BAC water benzyl alcohol alone irritates the nasal lining