Although adverse reactions to intravenous, intramuscular or subcutaneous injection of 0.9% benzyl alcohol are not known to occur in man, experimental studies of small volume parenteral preparations containing 0.9% benzyl alcohol in several species of animals have indicated that an estimated intravenous dose up to 30 mL may be safely given to an adult without toxic effects
As you can see, there's a lot to consider when deciding between vitamin B12 injections vs pills
For randomised clinical trials, the Jadad scale ( To complement the Jadad score, the Cochrane Risk of Bias Tool (RoB 2) (Sterne et al., 2019) was also used for RCTs to provide a domain-based qualitative evaluation, assessing risks related to selection, performance, detection, attrition, and reporting
They are: Contaminated or mislabelled compounded products research-grade vs pharmaceutical-grade manufacturing matters enormously Incorrect dosing without clinical oversight, patients routinely underdose (no effect) or overdose (unknown risk) Drug interactions particularly relevant if you are on GLP-1 therapy, immunosuppressants, or anti-inflammatory medications
If hunger is the main driver of weight regain, GLP-1/GIP strategies tend to be more directly matched to the problem