Serotonin syndrome and kratom: Causes, Symptoms, Treatment Serotonin syndrome refers to a group of symptoms, typically resulting from an increased level of serotonin, a chemical your neurons produce, in your brain. Certain substances and drugs can trigger this, most commonly medicaments which are used to treat depression or manage pain. This syndrome is characterized by cognitive, autonomic, and somatic effects that can range from mild to severe. Often, substance users seeking the possible benefit of a non-prescribed pain treatment turn to an herb called kratom. Scientifically known as Mitragyna speciosa, kratom operates in a way similar to opioids. Users tout...