Buttock IM Injection Site: Master Safe 2025 Subcutaneous Injection Best Vitamin B12 Injection Sites: Where to Inject B12 PA Relief Injecting substances can expose individuals that use injection drugs to serious harm, but understanding the difference between safer and more harmful sites can help reduce these potential dangers. Here's a breakdown of Injection Techniques: Injection Routes & Angles Intradermal (ID) 1015 just under the skin (dermis) Subcutaneous (SC) 45 into fat Intravenous (IV) 25