How to Self Administer Subcutaneous & Intramuscular Injections 6 Benefits of L Carnitine Injections MedHealth 360 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 Subcutaneous Injection Sites and Instructions for Safe Self Administration The How matters just as much as the What. We put together this step by step guide so you never have to guess what you need,where to inject and the mistakes to avoid.