Intramuscular and Subcutaneous Injections Clinical Skills For subcutaneous injections, using shorter needles (4 5mm) is the safest choice to ensure medication stays in the fatty layer and avoids muscle injury. A 4mm needle is ideal, minimizing pain while keeping Lipo C for Fat loss, Energy and Metabolism Defy Medical Lipo shots. B12 injections. L Carnitine. OH MY They're everywhere. But what does the research actually say? As a medical provider, I owe my patients the facts not false promises. Let's Serenity Skin NY