The effects of l carnitine supplementation on inflammatory factors, oxidative stress, and clinical outcomes in patients with sepsis admitted to the intensive care unit (ICU): study protocol for a double blind, randomized, placebo controlled 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 L carnitine: Science Backed Benefits, Risks, and More L Carnitine: Benefits, Uses, and Side Effects Lifespan Research Institute