Injections are usually best for people who cant absorb B12 properly from food or tablets or who have specific health issues
Exocrine Pancreatic Insufficiency (EPI) : Dogs with this pancreatic condition lack the digestive enzymes necessary for food breakdown and utilization (including vitamin B12)
intravenous TB-4 Phase 1 safety and pharmacokinetics, no dose-limiting or serious adverse events (Ann N Y Acad Sci 2010;1194:223229): NCT00743769 Centers for Disease Control and Prevention
[2] [12] There is no established link between B12 supplementation and weight loss in individuals with normal B12 levels
Vitamin B12 injections are ideal for individuals experiencing fatigue, stress, or vitamin deficiencies
However, in patients treated with diclofenac and glucocorticoids, the risk of peptic ulcer and gastrointestinal bleeding may increase, so special attention should be given in case of prolonged treatment, even in the absence of serious gastrointestinal symptoms