Much ado about nothing: the peptide they say never worked B12 Injections at Home Safety Guide for Self Administration Infusion For Health Vitamin Shots Therapy Clinic in Dayton and Yellow Springs, OH AOD 9604: Advanced Peptide Therapy for Effective Fat Loss AOD 9604 Peptide: Fat Loss, Before and After Results, and How It Works Vitamin B12 shots are injected intramuscularly bypassing the digestive process,which means they start to work immediately.Typically my clients will experience positive effects between 24 72 hours