Revisiting the Role of Carnitine in Heart Disease Through the Lens of the Gut Microbiota Does L carnitine cause fishy body odor? Surprising Truth and Solutions Tonum L Carnitine Injections: Before and After Results 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