When to take L carnitine: Dosage, forms, and side effects 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: Definition, symptoms, and more Carnitine Molecule of the Month September 2003 Pharmacokinetics of L Carnitine Clinical Pharmacokinetics Springer Nature Link Berberine and L Carnitine: Safety, Benefits and Dosage Guide Bolt Pharmacy