Comparison of short term and long term effects of peroral L carnitine intake: clinical implications of elevated TMAO levels in cardiovascular complications CUD Deficiency Primary Carnitine Deficiency L carnitine supplements can cause a fishy odor in the breath, sweat, and urine. This is likely due to the formation of trimethylamine (TMA). TMA is also responsible for the pungent smell of Potential Adverse Effects of L Carnitine Marnys L Carnitine: Benefits, Risks, and Its Role in Fitness and Weight Loss WellnessPulse