Subcutaneous Injection: What It Is and How to Give One L carnitine is an amino acid derivative that plays a crucial role in the bodys energy production processes. As an injectable supplement, L carnitine has been employed to support various health L Carnitine Injection: Benefits, Dosage And Risks Intramuscular vs. Subcutaneous Injections: What's the Difference? Intramuscular (IM) shots go deep into the muscle for faster absorption, while subcutaneous (SubQ) injections are placed just under the skin for slower, more sustained