UMEM Educational Pearls

Category: Toxicology

Title: Case: 27 year old with hydroxychloroquine overdose

Keywords: hydroxychloroquine toxicity, overdose (PubMed Search)

Posted: 6/11/2020 by Hong Kim, MD
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A 27 year-old man with history of rheumatoid arthritis presents to the emergency department after ingestion of hydroxychloroquine (20 tablets of 200 mg/tablet). He complains of nausea/vomiting. He appears lethargic. What is the anticipated hydroxychloroquine toxicity and management?

VS: Temp: afebrile, BP: 95/55 mmHg, RR: 23 breaths/min, O2 saturation: 99%





Signs and symptoms of hydroxychloroquine toxicity includes:

  1. Cardiac: Na & K channel blockade, hypotension/shock, ventricular dysrhythmia
  2. CNS: CNS depression, seizure
  3. Electrolyte: hypokalemia

Patient’s initial ECG showed: QRS: 134 msec; QTc 710 msec. There is also a terminal R wave in aVR. no prior ECG was available.

He experienced intermittent non-sustained V tach.

K was 2.0 mmol/L. other laboratories were normal



ED/Hospital day 1:

  • The patient was intubated due to lethargy/CNS depression
  • NaHCO3 bolus was administered with narrowing of QRS interval to 128 msec with QTc 639 msec. 
  • NaHCO3 infusion
  • Diazepam 1 mg/kg (80 mg IV bolus plus intermittent IV bolus of 6 mg Q2 hrs [total 39 mg])
  • Brief requirement of epinephrine infusion at  0.25 mcg/kg/min. 

Hospital day 2:

  • QRS: 92 msec; QTc: 474 msec
  • Blood pressure normalized



  1. Cardiac toxicity (Na and K channel blockade) is the primary feature of hydroxychloroquine toxicity
  2. ECG should be obtained to evaluated for evidence of Na channel toxicity – if present, administer NaHCO3 IV bolus and continous infusion -- and QT prolongation.
  3. High dose diazepam: 1-2 mg/kg IV bolus, followed by continous infusion of 1 – 3 mg/kg/24 hour.
  4. If hypotensive, epinephrine is the preferred pressor of choice.



Chai PR et al. Intentional hydroxychloroquine overdose treated with high-dose diazepam: an increasing concern in the COVID-19 pandemic. J Med Toxicol. 2020 PMID: 32514696; PMCID: PMC7278768; DOI: 10.1007/s13181-020-00790-8