Best Vitamin B12 Injection Sites: Where to Inject B12 PA Relief A Retired RN About Vitamin B12 Injections B12 Injections at Home Safety Guide for Self Administration Infusion For Health B12 vitamin Store How to inject B12 in your arm How to Use These 4 IM Injection Spots Safely Types of Injection Injection is a method of administering medication directly into the body using a needle and syringe. It allows fast and effective absorption of medicines. Intradermal (ID)