Injectable vs Oral L Carnitine: Which Works Better? AWP 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 Comprehensive review of the expanding roles of the carnitine pool in metabolic physiology: beyond fatty acid oxidation Journal of Translational Medicine Springer Nature Link L Carnitine: Benefits, Side Effects, And Dosage, Per Dietitians