When Injectable L Carnitine Is Chosen Over Supplements for Wellness Support L Carnitine 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: Benefits, Side Effects, And Dosage, Per Dietitians Comprehensive review of the expanding roles of the carnitine pool in metabolic physiology: beyond fatty acid oxidation Journal of Translational Medicine Springer Nature Link