Do you or someone you love smell like fish? It could be Fish Odor Syndrome! #fishodorsyndrome #fishy #fishysmell #fishodor A recurring fishy odor could indicate a larger medical problem. When to take L carnitine: Dosage, forms, and side effects Does L carnitine cause fishy body odor? Surprising Truth and Solutions Tonum Does L carnitine cause fishy body odor? Surprising Truth and Solutions Tonum Did You Know? Some people report a fishy smell after supplementing with L carnitine. This happens because certain gut bacteria convert carnitine to trimethylamine, a malodorous compound found in rotting fish.