Competitive and syntrophic interactions for B12 exist between microbes in the gut
However, it is thought to be due to imprecise intra-arterial injection leading to arterial thrombosis and subsequently leading to pain, vasospasm, embolism, sympathetic nerve stimulation leading to necrosis in cutaneous, subcutaneous, adipose, and/or muscle tissues.[ , ] Diagnosis is mostly clinical
If the injury is resolving well, most patients complete the full cycle and then take a two to four week break before evaluating whether a second cycle is needed
Thorough documenting of infusion start and stop times, medication information, and clinical indications is critical for demonstrating medical necessity and avoiding claim errors
If the primary benefit is energy improvement that could be achieved with $15/month oral B12 plus a multivitamin, the injection may not be cost-justified