Injectable L Carnitine: Does It Really Work for Fat Loss? 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 solution for injection 1g 5ml Help SA CPHI Online Assessing the In Vitro and In Vivo Performance of L Carnitine Loaded Nanoparticles in Combating Obesity What is L Carnitine, L Carnitine is an amino acid that plays a role in energy production and fat metabolism. Its found in foods like red meat, fish, and dairy, and also available as a supplement.,