Veterinary Strength Healthy Heart for Dogs & Cats PDF) [L carnitine treatment and fish odor syndrome: an unwaited adverse effect]. Acetyl L Carnitine: Benefits and Side Effects Gene Food Fish Odor Carnitine TikTok 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 CARNITINE (L CARNITINE, ACETYLCARNITINE) Neuroneeds