The comments come after Tottenham goalkeeper Hugo Lloris lost consciousness in an accidental collision with Romelu Lukaku during Sunday's 0-0 draw at Everton, with Spurs coming in for criticism after allowing the Frenchman to continue playing.
Brain injury charity Headway described the decision as "dangerous and irresponsible", adding that players should be removed from any game immediately after sustaining a concussion.
The PFA believes clubs should have the decision of whether players continue in a game taken from them, and are looking to firm up the laws regarding the issue.
John Bramhall, the organisation's deputy chief executive, said in a statement: "When treating a player on pitch, it can be very difficult to determine the severity of a head injury.
"It is important to take the pressure off the players, club medical staff, and the manager - removing the need for them to make a very difficult decision.
"If anyone suffers a severe trauma to the head and loses consciousness, then they should be required to leave the field of play automatically.
"The PFA will continue to work with the stakeholders within the game, to evaluate what guidelines are currently in place and to see if and how they need to be improved to provide better protection for all those involved in the game."
Tottenham responded to the comments from Headway on Monday, with the club's head of medical services Wayne Diesel stating he was "totally satisfied that he (Lloris) was fit to continue playing".
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