LeanShots Liquid L Carnitine Shot (3000mg) NutraBio Brands 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 Where to Inject L Carnitine for Maximum Fat Loss Benefits 6 Benefits of L Carnitine Injections MedHealth 360 What is the proper dosage and administration of injectable L Carnitine? Injectable l carnitine has 100% bioavailability and it's a supplement, not steroid. Even as a natty you can use and it can also help you in your bulking process, not just in fat