Subcutaneous Injection: What It Is and How to Give One Subcutanous injection self administration South Tees Hospitals NHS Foundation Trust 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: What Is It and How to Give One Ro L Carnitine Injectable Factor Health MD