Brain injury charity Headway wants stronger action on concussion protocol following a "concerning" incident with Manchester United defender Harry Maguire on Saturday.
Maguire showed signs of discomfort following a collision with Fulham striker Rodrigo Muniz.
He was assessed by United's medical staff before being allowed to continue.
Headway chief executive Luke Griggs said it was "concerning for a number of reasons".
The England defender had a cut above his eye after his head made contact with the shoulder of Muniz just two minutes into the Red Devils' 1-0 win at Craven Cottage.
He passed medical checks and was deemed fit to continue but referee John Brooks called for another assessment with around an hour played when Maguire looked dazed following a headed clearance.