Comparison of short term and long term effects of peroral L carnitine intake: clinical implications of elevated TMAO levels in cardiovascular complications 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 The effects of L carnitine supplementation on lipid profiles in adults: A systematic review and dose response meta analysis ScienceDirect L Carnitine is Underrated. New Meta Review Reminds Us Why.