L Carnitine Injection Levocarnitine IV 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 11 Urine Smells Explained In Everyday Life Some food and drink habits show up in a very ordinary place, and people are always a little surprised by how fast it happens. A Trimethylaminuria (Fish Odor Syndrome or TMAU)