Injectable vs Oral L Carnitine: Which Works Better? AWP Product Spotlight! L Carnitine injections infusions and the benefits thereof! Skinny Shot Injection L carnitine supplements bioavailability is very less and according to some studies it takes 8 to 12 weeks for for loss results, so if you decide to supplement with oral L carnitine 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 6 Benefits of L Carnitine Injections MedHealth 360