B12 Shot Guide: Benefits, Dosage & Side Effects BodySpec How Long Does Vitamin B12 Take to Work? Timeline & Signs Performance Lab Vitamin B Supplementation: Oral Capsules vs. Sublingual Tablets AZ Dietitians Vitamin B12 Injections: Benefits for Your Health 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