Fish odour syndrome CMAJ What are the effects and side effects of using L Carnitine IM? L Carnitine Benefits for Male Erectile Dysfunction 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. 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