Introduction
Ondansetron is an FDA-approved selective serotonin 5-hydroxytryptamine3 (5-HT3) receptor antagonist with several therapeutic applications and is commonly indicated as an anti-emetic agent for patients with severe nausea and vomiting(1). Ondansetron has multiple mechanisms of actions by blocking serotonin on central sites and peripheral sites. Central antagonism targets the chemoreceptor trigger zone located on the fourth ventricle floor, while peripheral action affects the vagus nerve(2,3). As a result, the trigger zone and the vagus nerve play a crucial role in the regulation of serotonin and are responsible for triggering nausea and emesis originating from the stomach(4,5). Typically, ondansetron is indicated in patients with a history of chemotherapy, radiotherapy, drug poisoning, antidepressant therapies, head trauma, or gastrointestinal motility disorders that lead to symptoms of emesis(6). A meta-analysis by Piechotta et al. revealed that ondansetron alone or in combination with other antiemetic agents effectively controlled the vomiting due to chemotherapy in adults(6). However, recent studies have also shown the efficacy of ondansetron in reducing the number of vomiting episodes in pediatric patients with acute gastroenteritis(7, 8).
The majority of 5-HT3 receptor antagonists have been associated with electrocardiogram changes that are insidious and asymptomatic in onset(9). Common side effects of ondansetron include headaches, dizziness, and diarrhea or constipation(10). However, it is a rare entity to observe potentially fatal reactions such as coronary vasospasms and hypersensitivity skin reactions from ondansetron despite having no allergies to the drug. In this paper, we present a rare case of an anaphylactoid reaction with spontaneous coronary vasospasms in response to intravenous ondansetron.