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 Amazon.com: Benevolent L Carnitine Supplement High Potency 1500mg L Carnitine Tartrate Fast Absorbing, Convert Fat to Energy, Support Lean Muscle, Boost Workout Performance & Metabolism 120 Vegan Capsules : Health & Household 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. Fishy Smell from L Glutamine TikTok PDF) [L carnitine treatment and fish odor syndrome: an unwaited adverse effect]. Force Factor L Carnitine Liquid, Berry, 16 fl oz (473 ml) Walmart.com