Suspected carbon monoxide poisoning (headaches in several people, in winter)
BioMG follows French guidelines. Adapt it to the guidelines and the tests available where you practise.
Current symptoms or ongoing exposure: emergency
- Have the premises evacuated (without exposing yourself) and call 15 (emergency services): diagnosis and treatment are a matter for the emergency services and hospital.
- Exposure measured by the emergency services or in the emergency department: blood carboxyhaemoglobin or CO in exhaled air, as early as possible after removal.
- Report any suspected or confirmed poisoning to the ARS (regional health agency), the municipal health and hygiene service or the poison control centre (in Paris and the inner suburbs: poison control centre and the central laboratory of the Préfecture de Police).
Past suspected exposure (recurrent headaches at home or at work, patient asymptomatic in the practice)
Laboratory tests, to be drawn as early as possible after leaving the suspected place
- Carboxyhaemoglobin (blood carbon monoxide); state smoking status and the time of leaving the suspected place
- Blood drawn into a gas syringe (venous or arterial blood), never into a heparinised tube, reaching the laboratory within 30 minutes: check before prescribing that the laboratory can perform it [11].
- Report the suspicion to the ARS, the municipal health and hygiene service or the poison control centre, which organise the investigation; the source must be identified and neutralised.
Also consider
- Raised haemoglobin? In a smoker or someone exposed to CO, see the page "Polyglobulie".
Do not order
- Delaying the measurement by several hours, or doing it after oxygen, to “rule out” poisoning: COHb falls rapidly after exposure ends (half-life 74 minutes on average on 100% oxygen) [5].
- Taking COHb on a heparinised tube (with or without gel) or sending it delayed to a distant laboratory: analytical interference and risk of diagnostic error; blood gas syringe, to the laboratory in under 30 minutes [11,13].
Sources (13)
- Santé publique France. Monoxyde de carbone : en bref (dossier thématique), consulté le 11 octobre 2026.
- Santé publique France. Quels sont les signes d'une intoxication au monoxyde de carbone ? (dossier thématique), consulté le 11 octobre 2026.
- Santé publique France. Comment une intoxication au monoxyde de carbone est-elle diagnostiquée ? (dossier thématique), consulté le 11 octobre 2026.
- Santé publique France. Monoxyde de carbone : données — définitions d'intoxications au monoxyde de carbone (définition de cas du système de surveillance, circulaire du 14 décembre 2005), consulté le 11 octobre 2026.
- Weaver LK, Howe S, Hopkins R, Chan KJ. Carboxyhemoglobin half-life in carbon monoxide-poisoned patients treated with 100% oxygen at atmospheric pressure. Chest. 2000;117(3):801-8.
- Santé publique France. Monoxyde de carbone : notre action (système de surveillance, signalement), consulté le 11 octobre 2026.
- Jüttner B, Busch HJ, Callies A, et al. S2k guideline diagnosis and treatment of carbon monoxide poisoning. Ger Med Sci 2021;19:Doc13.
- American College of Emergency Physicians (Wolf SJ, Maloney GE, Shih RD, Shy BD, Brown MD). Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department With Acute Carbon Monoxide Poisoning. Ann Emerg Med 2017;69(1):98-107.e6.
- UK Health Security Agency. Carbon monoxide: toxicological overview. Mise à jour le 24 mai 2022.
- American College of Emergency Physicians (Shih RD, Tomaszewski CA, Kaji A, Diercks DB). A Critical Issue in the Management of Adult Patients Presenting to the Emergency Department With Acute Carbon Monoxide Poisoning. Ann Emerg Med 2025;85(4):e45-e59.
- CHU de Lille, pôle de biologie. Flash info biologie recours du 13 décembre 2024 : alerte produits de santé — recommandations relatives au dosage sanguin de la carboxyhémoglobine (HbCO), relayant une information du CORRUSS (ministère chargé de la santé).
- Assurance maladie. Nomenclature des actes de biologie médicale (NABM), version 105 : acte 1680 (oxyde de carbone du sang).
- Institut national de recherche et de sécurité (INRS). Base de données Biotox : oxyde de carbone (dosages de la carboxyhémoglobine et de l'oxyde de carbone sanguins). Mise à jour décembre 2022.