B48-13 Severe Serotonin Syndrome With Acute Respiratory Failure Following Ayahuasca and Dextromethorphan Use: A Case Report

A 46-year-old man developed life-threatening serotonin syndrome after consuming ayahuasca at a retreat and later taking dextromethorphan and diphenhydramine. He presented with agitation, hyperthermia, tachycardia, and respiratory failure requiring intubation and intensive care. Treatment with cyproheptadine and midazolam led to full recovery within three days. The case highlights the dangerous interaction between ayahuasca's monoamine oxidase inhibitors and over-the-counter serotonergic medications, which can synergistically cause severe toxicity.

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Abstract

Abstract Introduction Ayahuasca is a psychoactive brew used in Amazonian ceremonies, containing monoamine oxidase inhibitors (MAOIs) from Banisteriopsis caapi and N,N-dimethyltryptamine (DMT) from Psychotria viridis or Diplopterys cabrerana. Its global use has expanded for perceived antidepressant and anti-addictive effects. However, its MAOI content predisposes users to serotonergic toxicity when combined with other serotonergic agents. Serotonin syndrome (SS) is a potentially fatal hypermetabolic condition that can progress rapidly to respiratory failure, requiring critical care management. Case Report A 46-year-old man with Factor V Leiden presented with agitation, hyperthermia, and psychomotor disturbance after ingesting an unknown substance. He had recently returned from an ayahuasca retreat, where he consumed the brew for three days. Afterward, he took Mucinex DM (containing dextromethorphan [DXM]) and diphenhydramine for cough and allergy symptoms.On arrival, his vitals were: respiratory rate 27/min, BP 166/98 mmHg, oxygen saturation 93%, and temperature 38.9 °C. Examination revealed coarse rhonchi, accessory muscle use, and tachycardia. Labs showed creatine kinase 1,432 IU/L and AST 47 IU/L. Urine toxicology was positive for benzodiazepines. ECG demonstrated sinus tachycardia with inferolateral T-wave abnormalities; imaging was unremarkable.He developed acute respiratory failure with alternating apneic and tachypneic episodes, requiring emergent intubation and ICU admission for suspected SS. Management included IV isotonic saline, oral cyproheptadine (2 mg every 2 hours), and IV midazolam infusion (1 mg/hour) for sedation and rigidity control. Over 24 hours, his hemodynamics stabilized, fever resolved, and ventilation normalized. He was extubated on ICU day 2 and discharged on hospital day 3 in stable condition. Discussion This case demonstrates the life-threatening interaction between ayahuasca and over-the-counter serotonergic medications such as DXM and diphenhydramine. The MAOI activity of harmala alkaloids inhibits serotonin breakdown, while DXM enhances serotonin activity, producing synergistic toxicity. This combination can trigger severe SS with hyperthermia, autonomic instability, and neuromuscular hyperactivity, leading to respiratory failure.Early recognition and prompt airway management are critical. Rapid intubation and ICU care resulted in full recovery. This case underscores the dangers of ayahuasca use with serotonergic agents and the need for clinician awareness of such toxic interactions. This abstract is funded by: None