What happens if my child might have a head injury or concussion?

Under US Soccer's Concussion Initiative for small-sided games:

• Play is stopped so the player can be checked.
• If the player leaves the field to be evaluated, a substitution can be made right then.
• The player may not return to the game unless a health care professional or certified athletic trainer has cleared them.
• If a coach or parent insists on returning the player without that clearance, the referee ends the game.

At U8 (4v4) there's usually no referee, so the coaches and parents are responsible for applying this.

The CDC's HEADS UP guidance says the same: remove the child from play right away if a concussion is suspected, and keep them out for the rest of that day and until a health care provider clears them.