BMJ Case Reports 2018; doi:10.1136/bcr-2018-224185
  • Rare disease

Dangerous mistake: an accidental caffeine overdose

Open Access
  1. Martinho Fernandes1
  1. 1 Department of Internal Medicine, Centro Hospitalar Barreiro Montijo EPE, Barreiro, Portugal
  2. 2 Department of Cardiology, Centro Hospitalar Barreiro Montijo EPE, Barreiro, Portugal
  1. Correspondence to Dr Ana Andrade, anaandrade987{at}
  • Accepted 25 May 2018
  • Published 8 June 2018


Caffeine (1,3,7-trimethylxanthine) is a natural product commonly presented in food’s composition, beverages and medicinal products. Generally, it is thought to be safe under normal dosage, yet it can be fatal in case of severe intoxication. We report a case of a healthy 32-year-old woman who went to the local emergency department (ED) 30 min after ingesting, accidentally, 5000 mg of anhydrous caffeine for a preworkout supplement. At the ED, she presented an episode of presyncope followed by agitation. ECG showed polymorphic broad complex QRS tachycardia and arterial blood gas revealed metabolic acidaemia with severe hypokalemia. The dysrhythmia was successfully treated with intravenous propranolol. Acid–base and hydroelectrolytic disorders were also corrected. A persistent sinus tachycardia was observed in the first 2 days in the ward and 5 days later she was discharged asymptomatic with internal medicine follow-up.


  • Contributors AA, CS, MP and MF: contributed to the planning and conduct of this article. AA: collected, analysed and discussed, with MP, all data in this clinical case; prepared the manuscript draft with support from CS and MF, with critical feedback and helped organize the manuscript. AA and CS: analysed the review and rectified the article.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:

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