Benefits of B12 Injections for Optimal Health Vitamin B12 IM Injectable at Philly IV Lounge Dr. prescribed B12 injections. Pharmacy only gave me vials. Where do you get your needles and syringes? What size?? Where do I inject? : r B12_Deficiency How to Give a B12 Injection: Step By Step Instructions Types of injections explained Intramuscular (IM) Inserted at 90 to deliver medication deep into the muscle, allowing relatively fast absorption due to rich blood supply. Subcutaneous (SC) Inserted at about 45 Subcutaneous (SC) and Intramuscular (IM) Injections Must Knows for Subcutaneous administration: Pinch skin with non dominant hand and hold syringe with dominant hand Always inject: 2 inches away from umbilicus (for abdomen) 3 inches