When to take L carnitine: Dosage, forms, and side effects L Carnitine Injections: A Clinical Guide for Practitioners National Medical Resources Inc Injectable L Carnitine Weight Wise Weight Loss Center 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