The combined use of Angelica sinensis and fentanyl injection may cause serotonin syndrome: a case report

Serotonin syndrome is a potentially life-threatening condition caused by excessive concentrations of synaptic 5-hydroxytryptamine. At present, due to the absence of gold-standard laboratory diagnostic test and the variability of its clinical manifestations, it could be confused with other clinical conditions, leading to delayed diagnosis that may compromise patient prognosis and survival. This case report depicted a 59-year-old Chinese man who may developed serotonin syndrome during gastrointestinal endoscopy anesthesia with fentanyl injection while taking Angelica multiple times, resulting in the failure of gastrointestinal endoscopy. Related clinical symptoms were specifically manifested as generalized muscle clonus, sweating, fever, elevated blood pressure, tachycardia, and metabolic acidosis. The patient improved after symptomatic treatment. This case reveals that the combined use of Angelica sinensis and fentanyl injection may cause serotonin syndrome during surgery, which could threaten the patient's life and thus affect the operation. This case report highlights the importance of recognizing serotonin syndrome, identifying its clinical manifestations, and implementing timely clinical management strategies. It also emphasizes the potential risk of adverse reactions associated with traditional Chinese medicine, particularly avoiding combined use before and after anesthesia.