What are the benefits and side effects of L carnitine (Levocarnitine)? 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 Comparison of short term and long term effects of peroral L carnitine intake: clinical implications of elevated TMAO levels in cardiovascular complications bodyathlon Fishy Odor Syndrome (Trimethylaminuria): Causes, Symptoms, Diagnosis, and Treatment Mister Blister