Any advice for fishy smell with L carnitine? 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: Benefits, Uses, and Side Effects Lifespan Research Institute Do you or someone you love smell like fish? It could be Fish Odor Syndrome! #fishodorsyndrome #fishy #fishysmell #fishodor