Trimethylaminuria: Definition, symptoms, and more 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 Trimethylaminuria: Understanding and Treating Fish Odor Syndrome Malodorous biogenic amines in Escherichia coli caused urinary tract infections in womena metabolomics approach Scientific Reports Development and Application of a UPLCMRMMS Method for Quantifying Trimethylamine, Trimethylamine N Oxide, and Related Metabolites in Individuals with and Without Metabolic Syndrome