Vitamin B12 deficiency, if left untreated, can lead to neurological problems
10.1089/acm.2006.12.881 Summary Keywords vitamin B12, efficacy, bioavailability, therapeutic approaches, meta-analysis, cobalamin Citation Mazur M, Ndokaj A, Salerno C, Vallone J, Ardan R, Bietolini S, Carrouel F, Wilk A, Sarig R, Ottolenghi L and Bourgeois D (2025) Efficacy of sublingual and oral vitamin B12 versus intramuscular administration: insights from a systematic review and meta-analysis
Case reports and pharmacovigilance entries rarely give enough detail to show that one form is clearly safer
If the vial was left out overnight, the solution may still be usable, but potency could be reduced
When adverse effects occurred, they were typically mild and transient, with the most common being mild to moderate headaches (similar frequency to placebo groups), minor injection site reactions (redness, slight swelling), and gastrointestinal effects at higher oral doses (nausea, diarrhea)