Does Carnitine Cause Body Odor? Lume Deodorant Acetyl L carnitine in the treatment of peripheral neuropathic pain: a systematic review and meta analysis of randomized controll 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. L Carnitine L Tartrate Powder True Protein A recurring fishy odor could indicate a larger medical problem.