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 Subcutanous injection self administration South Tees Hospitals NHS Foundation Trust HRT Medics Nutraceutical Injections L Carnitine injection is recommended at 1 ampule every 2 3 days for best results. The L Carnitine is taken intravenously either by normal injection or using a butterfly needle. After taking this L Carnitine, you L Carnitine Intramuscular shot ELIXR IV Therapy Where to Inject L Carnitine for Maximum Fat Loss Benefits