L Carnitine: Benefits, Uses, Side Effects, and More L Carnitine: Benefits, Side Effects, And Dosage, Per Dietitians Should I use L Carnitine on rest days or just before workouts? L Carnitine: Benefits, Side Effects, And Dosage, Per Dietitians 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