The Union Cycliste Internationale (UCI) has updated its policy to ban the repeated inhalation of carbon monoxide (CO) from 10 February 2025 onwards and has introduced measures to ensure the participation of the best teams in top-tier road events.
As reported previously, the UCI has repeatedly urged the World Anti-Doping Agency (WADA) to “take a stand” against CO inhalation by cyclists. The substance is used by the world’s top cyclists to drive an increase in Erythropoietin (EPO), haemoglobin levels and VO2max.
CO prevents oxygen molecules from binding with haemoglobin, which normally supplies the body with oxygen. Therefore, the body adjusts to the lack of oxygen and provides the athlete with a surge of Erythropoietin (EPO), simulating altitude training. CO increases total haemoglobin mass which increases endurance. Furthermore, several athletes and coaches argue that the practice also enables more accurate blood analysis.
However, the practice is very contentious due to its potentially lethal nature. Repeatedly inhaling the gas has the potential to cause artificial hypoxia. Hypoxia is low levels of oxygen in your body tissues. It causes confusion, restlessness, difficulty breathing and rapid heart rate.
Due to this, the Management Committee of the UCI met in Arras (France) on 31 January and 1st February, alongside the 2025 UCI Cyclo-cross World Championships, which are being held in Liévin from 31 January to 2 February.
To protect the health of riders, the UCI Management Committee approved a ban on the repeated inhalation of (CO). The ban will come into force on 10 February 2025.
UCI President David Lappartient expressed: “The UCI takes a bold and necessary stance by banning the repeated use of carbon monoxide inhalation on medical grounds. Our priority is to protect the health and safety of our athletes and today’s decision is another significant step in this direction.”
The new regulation forbids the possession, outside a medical facility, of commercially available CO re-breathing systems connected to oxygen and CO cylinders. This ban applies to all licence-holders, teams and/or bodies subject to the UCI Regulations and to anyone else who might possess such equipment on behalf of riders or teams.
The inhalation of CO will remain authorised within a medical facility and under the responsibility of a medical professional experienced in the manipulation of this gas for medical reasons and in line with the following restrictions: only one CO inhalation to measure total Hb mass will be permitted. A second CO inhalation will only be authorised two weeks after the initial Hb measurement.
For riders in UCI WorldTeams, UCI Women’s WorldTeams and UCI ProTeams, any CO inhalation for the purpose of determining total Hb mass must be recorded in the medical file established for each athlete, in compliance with Articles 13.3.020 to 13.3.026 of the UCI Medical Rules.
Even though the UCI has taken a firm stand by officially banning the repeated inhalation of CO, the UCI’s ban still remains independent of the World Anti-Doping Code and the UCI Anti-doping Regulations. The UCI continues to request that the World Anti-Doping Agency (WADA) takes a position on the repeated use of CO in and out of competition.
Additionally, the UCI has also introduced measures to ensure the participation of the best teams in top-tier road events. The UCI Management Committee approved a modification to the participation rules for the UCI WorldTour and UCI Women’s WorldTour from 2026.
Under this new rule, it will be mandatory for all UCI WorldTeams to compete in the three Grand Tours (Giro d’Italia, Tour de France and La Vuelta Ciclista a España) and the five Monuments (Milano-Sanremo, Ronde van Vlaanderen, Paris-Roubaix, Liège-Bastogne-Liège, and Il Lombardia). From the remaining events on the UCI WorldTour calendar, UCI WorldTeams will be able to choose one event in which they do not compete.
No more than four UCI WorldTeams may be absent from the same event, and teams will not be permitted to be absent from the same event more than once during the three-year registration cycle (2026-2028). Any spot at a UCI WorldTour event left vacant by one of the 18 UCI WorldTeams will be offered by invitation to a UCI ProTeam.
The same participation rules will apply to UCI Women’s WorldTeams in the UCI Women’s WorldTour, but only for the following events: the Vuelta España Femenina by Carrefour.es, Giro d’Italia Women and Tour de France Femmes avec Zwift.
The UCI’s official statement can be viewed here - The UCI bans repeated inhalation of carbon monoxide, and introduces measures to ensure participation of best teams in top-tier road events | UCI
