location of b12 injection Best Vitamin Sites: Where to Inject B12 · PA Relief Benefits of Vitamin B12 Shots

Specific allergic manifestations consisting of swelling of eyelids, lips, pharynx and larynx, urticaria, asthma, and bronchospasm, sometimes with a concomitant fall in blood pressure

While B-12 is commonly found in various foods, some individuals may have difficulty absorbing it efficiently through the digestive system

Standard topical application struggles to get peptides through the skin barrier

The liver stores are a bit irrelevant to someone who has PA or a B12 absorption problem though because the mechanism that is used to release them relies on the same mechanism that is used to absorb most dietary B12 so accessing any stores is at best very inefficient

So the capsule-vs-sub q question for most peptides isnt a preference its forced by molecular weight