Case Definition: Paraquat

Clinical description

Ingestion of paraquat typically results in gastrointestinal (GI) signs and symptoms including oropharyngeal ulcerations, vomiting, diarrhea and GI bleeding. Patients also may have dyspnea and hemoptysis as a result of pulmonary edema or hemorrhage respectively, which can progress to pulmonary fibrosis over the course of days to weeks (1-4).

Laboratory criteria for diagnosis

  • A case in which paraquat is detected in urine, plasma, or serum.

-OR –

  • Detection of paraquat in environmental samples. (5-8)

Case classification

  • Suspected: A case in which a potentially exposed person is being evaluated by health-care workers or public health officials for poisoning by a particular chemical agent, but no specific credible threat exists.
  • Probable: A clinically compatible case in which a high index of suspicion (credible threat or patient history regarding location and time) exists for paraquat exposure, or an epidemiologic link exists between this case and a laboratory-confirmed case.
  • Confirmed: A clinically compatible case in which laboratory tests have confirmed exposure.

The case can be confirmed if laboratory testing was not performed because either a predominant amount of clinical and nonspecific laboratory evidence of a particular chemical was present or the etiology of the agent is known with 100% certainty.

Additional resources

  1. Bismuth C, Garnier R, Baud FJ, Muszynski J, Keyes C. Paraquat poisoning: an overview of the current status. Drug Saf 1990;5:243-51.
  2. Bismuth C, Garnier R, Dally S, Fournier PE, Scherrmann JM. Prognosis and treatment of paraquat poisoning: a review of 28 cases. J Toxicol Clin Toxicol 1982;19:461-74.
  3. Vale JA, Meredith TJ, Buckley BM. Paraquat poisoning: clinical features and immediate general management. Hum Toxicol 1987; 6:41-7.
  4. Gawarammana IB, Buckley NA. Medical management of paraquat ingestion. Br J Clin Pharmacol. 2011 Nov;72(5):745-57.
  5. NIOSH. NIOSH manual of analytical methods [online]. 2003. [cited 2013 Apr 5]. Available from URL:
  6. OSHA. Sampling and analytical methods [online]. 2010. [cited 2013 Apr 5]. Available from URL: icon.
  7. FDA. Food: Laboratory methods [online]. 2013. [cited 2013 Apr 5]. Available from URL: icon.
  8. EPA. Selected analytical methods: chemical methods query [online]. 2013. [cited 2013 Apr 5]. Available from URL: icon.
Page last reviewed: April 4, 2018