After a number of cases last season and at the World Cup when players continued to play after taking heavy blows to the head, the FA has tightened up its procedures in order to reduce the risk of concussion. The new guidelines state: "If there has been a confirmed or suspected period of loss of consciousness, the player must be removed from the field of play, and not be allowed to return.
"If there is any doubt as to the course of events, elucidation may be sought from officials or other players. In the event that there is video replay available pitch-side or in the players' tunnel, this could be used to clarify the course of events.
"Where no loss of consciousness is apparent, an on-field or touchline assessment will take place."
All Premier League matches must also feature a 'tunnel doctor', who will support teams' medical staff in recognising the signs of concussion.
Previously, the FA's rules stated that players who had sustained head injuries could resume playing if they received "clearance from a qualified medical practitioner".
Concussion became a hot topic last season after Tottenham Hotspur goalkeeper Hugo Lloris continued playing after appearing to momentarily lose consciousness during a game at Everton in November.
The France international looked dazed after being struck in the head by the knee of Everton striker Romelu Lukaku, but he insisted on playing on.
Brain injury charity Headway said that Spurs had been guilty of an "irresponsible and cavalier attitude" by allowing Lloris to continue.
At the World Cup, Alvaro Pereira of Uruguay played on after being knocked out in a collision with Raheem Sterling during a group game against England.