Stabilizing the enzyme in fish odor syndrome Urine smells like fish: Causes and treatment Compounded Carnitine (L) Injection Empower Pharmacy L Carnitine Linus Pauling Institute Oregon State University 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 Fumarate Olympian Labs