Sand IK, et al. - During this trial, the efficacy and tolerability of cetirizine were gauged by the authors as an add-on to standard therapy for neuromyelitis optica (NMO). Findings revealed that the Epworth Sleepiness Scale (ESS) remained fairly consistent throughout the study. Hence, it was determined that the addition of cetirizine to standard therapy was safe and well tolerated in patients with NMO. It also led to a reduction in the relapses.