When to take L carnitine: Dosage, forms, and side effects According to a randomized, double blind, placebo controlled clinical trial published in Elsevier journal Research in Autism Spectrum Disorders (2013), l carnitine supplementation demonstrated a significant therapeutic benefit in children diagnosed with The effect of l carnitine supplementation on mortality and clinical outcomes in ventilator dependent critically ill patients with obesity and COVID 19: Protocol for a randomized double blind placebo controlled trial ScienceDirect Is it safe to take L carnitine with levothyroxine (thyroid medication)? L Carnitine: Benefits, Side Effects, And Dosage, Per Dietitians