Melanotan II 99%+ Pure Peptide Amino Club Amino Club 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 Why Does L Carnitine Smell Like Fish TikTok Buy Melanotan 2 Peptide 99%+ Pure Melanotan 2 for Research Did You Know? Some people report a fishy smell after supplementing with L carnitine. This happens because certain gut bacteria convert carnitine to trimethylamine, a malodorous compound found in rotting fish.