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. Is L Carnitine Safe? Watch FIRST BEFORE Taking L Carnitine Supplements L Carnitine Avoid Fishy Smell TikTok 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. Any advice for fishy smell with L carnitine? A recurring fishy odor could indicate a larger medical problem.