When a Routine Drug Turns Toxic: A Case of Methotrexate - Induced Multi-Organ Dysfunction

Girin Ray and Satyaki Basu*

Department of Internal Medicine, KPC Medical College and Hospital, Jadavpur, Kolkata, India

^*Correspondance to: Satyaki Basu 

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Abstract:

Background: Methotrexate (MTX), a folic acid antagonist used widely in oncology, rheumatology, and dermatology, carries significant risk for acute toxicity. This case report presents a middle-aged male with psoriatic arthritis who experienced severe, life-threatening multi-organ dysfunction following MTX exposure. Case Presentation: The patient presented to the emergency department with acute-onset severe mucocutaneous ulcerations, erosive mucositis, respiratory distress (SpO2 89%), and dysphagia. Laboratory investigations revealed profound pancytopenia (hemoglobin 7.6 g/dL, total leucocyte count 1,190/mm3), acute kidney injury (urea 126 mg/dL, creatinine 1.5 mg/dL), and markedly elevated inflammatory markers (ESR 62 mm/hr). Upper gastrointestinal endoscopy demonstrated diffuse erosive lesions extending from the oropharynx to the esophagus. Respiratory acidosis (pH 7.3, pCO₂ 62.1 mmHg) developed, complicated by hospital-acquired pneumonia secondary to severe neutropenia. Management and Outcome: Upon recognition of MTX toxicity, immediate interventions included drug discontinuation, leucovorin (folinic acid) rescue therapy at 100 mg three times daily, and granulocyte colony-stimulating factor (filgrastim) administration to support hematopoietic recovery. Broad-spectrum antimicrobial therapy with meropenem and tigecycline was initiated for nosocomial infection, and non invasive ventilation (BiPAP) was provided for respiratory support. At discharge, the patient demonstrated complete resolution of hematologic abnormalities and mucocutaneous lesions, with hemoglobin 13 g/dL, total leucocyte count 8,000/mm3, platelets 3.5 × 10⁵/mm³, and oxygen saturation 99% on room air. Clinical Significance: This case emphasizes the critical importance of early recognition of MTX toxicity through mucocutaneous manifestations and hematologic abnormalities, the role of prompt drug discontinuation and leucovorin rescue in improving outcomes, and the necessity for aggressive management of secondary complications including infection and respiratory.

Keywords:

Methotrexate

Cite the Article:

Girin Ray. When a Routine Drug Turns Toxic: A Case of Methotrexate - Induced Multi-Organ Dysfunction. Ann Clin Case Rep. 2025; 10: 2803..