Background <p>Obsessive-Compulsive Disorder (OCD) affects approximately 2–3% of the global population and is associated with significant functional impairment and reduced quality of life. Despite its widespread impact, pharmacological treatments approved by the U.S. Food and Drug Administration (FDA) for OCD remain limited. Vortioxetine is a multimodal antidepressant that obtained its FDA approval in December 2013 for Major Depressive Disorder (MDD) and has shown to have some potential benefits in terms of cognitive aspects and global manifestation of symptoms. The purpose of this study is to assess the effectiveness and safety of vortioxetine as adjunctive treatment in patients with a diagnosis of OCD.</p> Methods/design <p>A randomized, double-blind, placebo-controlled superiority trial, developed in accordance with CONSORT guidelines, will assess the efficacy and safety of vortioxetine in individuals diagnosed with OCD. A total of 114 participants who meet all eligibility criteria will be recruited and randomly allocated, using block randomization, into two equal treatment arms (<i>n</i> = 57 per group) following informed consent. The sample size provides 80% statistical power at a 5% significance level to detect a clinically meaningful difference of 5 units between the intervention and control groups. The experimental group will receive vortioxetine combined with escitalopram, and the control group will be administered a placebo with escitalopram. Demographic characteristics and disease profile at baseline will be collected using Case Report Forms (CRFs). The Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the Clinical Global Impressions (CGI) will be used to evaluate the outcomes at 4, 8, and 12 weeks. The Adverse Events and Side Events Checklist (ASEC) will document any adverse events reported by the patient throughout the trial participation.</p> Discussion <p>Vortioxetine’s unique pharmacological profile may offer significant benefits to managing cognitive symptoms and improving the quality of life of OCD patients. This clinical trial aims to provide evidence on the clinical value and safety of vortioxetine in the management of OCD in order to advance the optimization of more effective and personalized treatment plans.</p> Trial registration <p>The trial was registered with the Clinical Trials Registry - India (CTRI) (registration ID: CTRI/2023/12/060748) on December 26, 2023.</p>