What Are L Carnitine Injections Used For? L Carnitine ALC (Acetyl L Carnitine), 100 vegan capsules Aliness.co.uk 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 vs Oral L Carnitine: Which Works Better? AWP 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.,