L Carnitine 3500 Metabolic Nutrition Does L carnitine cause fishy body odor? Surprising Truth and Solutions Tonum L Carnitine is an amino acid that supports weight loss as it is a fat burning supplement. L Carnitine Push is a direct and quick IV infusion procedure that can be done on a weekly 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 Trimethylaminuria: Definition, symptoms, and more