Best Vitamin B12 Injection Sites: Where to Inject B12 PA Relief How Quickly Does B12 Shot Work? Duration of Benefits The Magic Red Shot Lets talk Vitamin B12 Some people need the magic red shot (AKA a B12 IM injection) instead of just taking an oral supplement. Because heres the thing: You can swallow all Vitamin B12 Deficiency? Heres the best way to treat it!, Many people take oral or sublingual tablets, but they may not always be effective especially if absorption is poor., The active injectable