Survival Following Acute Moderate-Dose Paraquat Dichloride Poisoning: A Case Report of Multimodal Immunosuppressive and Antioxidant Management With 25-Day Radiological Follow-Up

Abstract

Background: Paraquat dichloride is a highly toxic dipyridyl herbicide with no specific antidote, responsible for significant morbidity and mortality across South and Southeast Asia, predominantly through deliberate self-ingestion. Moderate-dose ingestion, corresponding to an estimated elemental dose of 20–40 mg/kg, carries a reported mortality of 40–70%, with progressive pulmonary fibrosis representing the primary mechanism of late death. Timely multimodal intervention targeting oxidative stress, alveolar inflammation, and fibroblast proliferation remains the cornerstone of management in the absence of an antidote.

Case Presentation: A 20-year-old male with no known comorbidities presented to the emergency department following deliberate ingestion of approximately 30 mL of paraquat dichloride 24% soluble liquid, corresponding to an estimated elemental dose of approximately 120 mg/kg. He was managed with immediate gastric decontamination using activated charcoal, intravenous and oral N-Acetylcysteine, pulse methylprednisolone, cyclophosphamide with Mesna uroprotection, antioxidant vitamins, and urinary alkalinization with sodium bicarbonate. Supplemental oxygen was deliberately withheld throughout, given the established oxygen-dependence of paraquat's redox cycling mechanism. A transient acute kidney injury developed around Day 8 and resolved fully with conservative management without requiring renal replacement therapy. Serial chest radiographs and high-resolution computed tomography of the chest demonstrated no pulmonary fibrosis throughout the fourteen-day admission. An outpatient chest radiograph obtained at twenty-five days post-ingestion confirmed continued pulmonary normalcy.

Conclusion: This case demonstrates that moderate-dose paraquat poisoning can achieve a favorable outcome with early, protocol-driven multimodal management. Serial radiological monitoring and deliberate avoidance of supplemental oxygen are critical and often underappreciated components of successful management.