Some important factors to consider include allergic responses, injection site reactions, electrolyte imbalances, kidney and liver function, skin-lightening concerns, drug interactions, gastrointestinal disturbances, and long-term safety
Those with diseases that affect the gut, such as Crohns disease or celiac disease, are also at risk ( Summary Those at greatest risk of vitamin B12 deficiency are vegans and vegetarians, who get little to no B12 from the diet
Around the 2.4 mg dose, values near 184 hours have been reported in program summaries
Liu et al., 2018)
For a cosmetic outcome, this risk-to-benefit calculation is considerably less favourable than a topical skincare ingredient with decades of safe use