Third, it has toxicological uses as an adjunct in lead and ethylene glycol poisoning and intravenous dosing can cause anaphylaxis, so the IM/SC route is preferred
These are not conservative estimates
If a patient is truly deficient and cannot absorb oral B12, injections are lifesaving and the benefits outweigh the small risk
without enough B12, oxygen delivery drops, leaving you breathless and tired
In the withdrawal trial, continuing preserved loss far better than switching to placebo, which regained about 14% over a year. The metabolic benefit fades in proportion to the weight regained, so a taper plus protein and resistance training beats a hard stop
They also play a role in maintaining physiological homeostasis, such as cognition, blood pressure, feeding behavior, water balance, glucose metabolism, pain, and response to stress [7]