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 L Carnitine: What it's used for, benefits and how to take it correctly Justloading Does Carnitine Cause Body Odor? Lume Deodorant Does L carnitine cause fishy body odor? Surprising Truth and Solutions Tonum L Carnitine: Benefits, Uses, and Side Effects Lifespan Research Institute