What happens if a player has a suspected concussion?

The Laws of the Game 2026/27 (Law 5 and the off-field treatment protocol) treat a head injury such as concussion as a severe injury. A severe injury is one of the exceptions to the rule that an injured outfield player must leave the field and may not be treated on it. The player can be treated on the field.

Concussion substitutions (competition option): competitions may allow additional permanent concussion substitutions under The IFAB's protocol. Where a competition uses it:

• Each team may use a maximum of one concussion substitute in a match.
• The player with actual or suspected concussion takes no further part in the match, including penalties (penalty shoot-out).
• The opposing team then has the option of one additional substitute.
• The referee and other match officials are not part of a team's decision on whether a player should be substituted, and must not decide whether an injury qualifies for a concussion substitute.
• Officials should support the decision of the captain, coach or medical staff that an injured player cannot continue, which may mean delaying the restart until the player has left the field.
• Officials must inform the appropriate authorities if they have concerns that a concussion substitution was made inappropriately.

The Canada Soccer referee pages do not set out a separate concussion procedure for referees, so the points above come from the IFAB Laws.

Sources: IFAB Laws of the Game 2026/27, Law 5, Off-field treatment and assessment protocol, and Additional permanent concussion substitutions protocol (https://www.theifab.com/laws-of-the-game-documents/).