L Carnitine vs Pre Workout: Which Supplement Should You Take? L Carnitine Benefits, Uses, Dosage, Foods, Side Effects Dr. Axe 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 Amazon.com: Muscle Pharm L Carnitine 3000, The Ultimate Liquid L Carnitine Supplement for High Performance, Supports Metabolism, Hydration & Energy, Zero Sugar, Low Calories, Peach Nectarine Flavor, 32 Servings : Everything Else Fast&Up L Carnitine 3000 mg Triple Action Formula for Faster Fat Burn