Michael W Calik1,2 1Department of Biobehavioral Health Science, 2Center for Narcolepsy, Sleep and Health Research, University of Illinois at Chicago, Chicago, IL, United States Abstract: Narcolepsy is a neurological disease that affects 1 in 2,000 individuals and is characterized by excessive daytime sleepiness (EDS). In 60–70% of individuals with narcolepsy, it is also characterized by cataplexy or a sudden loss of muscle tone that is triggered by positive or negative emotions. Narcolepsy decreases the quality of life of the afflicted individuals. Currently used drugs treat EDS alone (modafinil/armodafinil, methylphenidate, and amphetamine), cataplexy alone (“off-label” use of antidepressants), or both EDS and cataplexy (sodium oxybate). These drugs have abuse, tolerability, and adherence issues. A greater diversity of drug options is needed to treat narcolepsy. The small molecule drug, pitolisant, acts as an inverse agonist/antagonist at the H3 receptor, thus increasing histaminergic tone in the wake promoting system of the brain. Pitolisant has been studied in animal models of narcolepsy and used in clinical trials as a treatment for narcolepsy. A comprehensive search of online databases (eg, Medline, PubMed, EMBASE, the Cochrane Library Database, Ovid MEDLINE, Europe PubMed Central, EBSCOhost CINAHL, ProQuest Research Library, Google Scholar, and ClinicalTrials.gov) was performed. Nonrandomized and randomized studies were included. This review focuses on the outcomes of four clinical trials of pitolisant to treat narcolepsy. These four trials show that pitolisant is an effective drug to treat EDS and cataplexy in narcolepsy. Keywords: narcolepsy, pitolisant, histamine