The effects of L carnitine on renal function and gene expression of caspase 9 and Bcl 2 in monosodium glutamateinduced rats BMC Nephrology Springer Nature Link Injectable L Carnitine How It Works & What to Expect? When Should You Take L Carnitine? MuscleTech 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 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. Creatine vs Carnitine: Do You Need Both? Differences Explained FeastGood.com