MLS has implemented a comprehensive concussion protocol in line with FIFA guidelines. When a player suffers a suspected head injury, they must be evaluated by independent medical staff on the sideline. If a concussion is suspected, the player cannot return to the match.
The protocol includes mandatory rest periods before a player can return to training and matches, following a graduated return-to-play process. MLS has also adopted the concussion substitution rule, which allows teams to make an additional substitution when a player is removed due to a suspected concussion. This ensures teams are not disadvantaged for prioritizing player safety.