How to Give a B12 Injection: Step By Step Instructions Types of injections explained! Understanding the angles: intramuscular (im) : injects deep into the muscle at 90. subcutaneous (sc) : goes under the skin at 45. intravenous (iv) : Subcutaneous Injection: What It Is and How to Give One B 12 Intramuscular vs. Subcutaneous Injection Best Vitamin B12 Injection Sites: Where to Inject B12 PA Relief Treating Severe Vitamin B12 Deficiency B12 IM Injection