L Carnitine Injection Levocarnitine IV Your urine's smell can reveal a lot about your health. A strong ammonia like odor could indicate kidney stress, while a fruity scent may suggest ketones. Sweet smelling urine might point to diabetes risk, Trimethylaminuria: Understanding and Treating Fish Odor Syndrome Urine normally has a slight smell, but some unusual and strong smells may be a sign that something's wrong. TMAU: Diet to reduce a fishy odour Dietitian's Life 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.