Injectable L Carnitine How It Works & What to Expect? 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 Lets talk about L Carnitine, If youre in the gym community, youve probably heard of L Carnitine but what actually is it?, L Carnitine is a naturally occurring compound that plays a role in helping Amazon.com: NOW Foods Supplements, L Carnitine 1,000 mg, Purest Form, Amino Acid, Fitness Support*, 100 Tablets : Health & Household