According to the National Academies of Sciences, Engineering, and Medicine (NAP), a safe highest level is called the tolerable upper intake level. Assessment of what amount is too much is based on animal and human studies, published evidence of adverse events, and professional agreement based on a committee of experts
In the UK, the standard NHS regimen for B12 deficiency without neurological involvement is hydroxocobalamin 1mg IM three times a week for two weeks
many pharmacies have take-back programs or specific instructions for safe disposal of injectables
For patients confirmed to need b12 supplementation, either approach works
Only the connection with skin bacteria is scientifically well proven at present, but also leaves numerous questions unanswered
The reconstituted solution must be inspected for clarity and absence of particulates before use