Terry almost died in the 2007 Carling Cup final when he swallowed his tongue while unconscious.
He has also played with face masks and plaster casts.
Terry, 29, returns for the Double winners at West Ham today after missing England's Euro 2012 double header with a hamstring problem.
Ancelotti said: "He has to have more recovery time than when he was 25. It's normal behaviour. He needs to have more rest if he wants to stay at the top level for a long time.
"I can use them, a Drogba or Terry, if they're not 100 per cent, but I need to know.
"He took the right decision with the national team.
"Terry is a player with a strong character. He's a player who loves to play for the shirt. But he has to be realistic."