L Carnitine Injection Levocarnitine IV Understanding Urine Smells: Causes and Solutions Amazon.com: SIRENLABS L Carnitine Elite Burn Liquid Keto Fat Burner and Metabolism Activator Fat Loss Support Keto Friendly Weight Loss Increase Energy Stimulant Free Strawberry Blast 3000mg (32 Servings) : Urine normally has a slight smell, but some unusual and strong smells may be a sign that something's wrong. 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. 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.