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 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 Injectable L Carnitine 500mg ml (20ml) : Amazon.ca: Health & Personal Care How to Self Administer Subcutaneous & Intramuscular Injections L Carnitine Linus Pauling Institute Oregon State University