How to Get Rid of Fishy Smell L Carnitine TikTok L Carnitine500, 500 mg, 120 Capsules Carnitine Deficiency: What Is It, Causes, Symptoms, and More Osmosis 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 Acetyl L Carnitine: Benefits and Side Effects Gene Food 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.