Opioid-Induced Nausea and Vomiting in Patients With Cancer: A Narrative Review.

Opioid-induced nausea and vomiting (OINV) represent a frequent and clinically significant complication in patients with cancer. They negatively affect adherence to analgesic therapy, pain control, and overall quality of life. Their pathophysiology is multifactorial and involves activation of the chemoreceptor trigger zone through dopaminergic and serotonergic pathways, impairment of gastrointestinal motility leading to delayed gastric emptying and reduced peristalsis, and vestibular modulation mediated by histaminergic and muscarinic pathways. These mechanisms are further influenced by individual susceptibility and pharmacological factors. Despite their clinical relevance, international guidelines primarily focus on chemotherapy- or radiotherapy-induced emesis, leaving a gap in the specific management of OINV. This narrative review synthesizes the available evidence and proposes a structured diagnostic and therapeutic approach tailored to this condition. A stepwise management model is presented, integrating non-pharmacological strategies and sequential pharmacological treatment according to the predominant pathophysiological mechanism. Explicit criteria for therapeutic failure and referral to specialized care are also included. This approach aims to optimize symptom control, support rational opioid rotation when indicated, and improve quality of life in patients with cancer receiving palliative care.