Shearer thinks that only Yohan Cabaye and Fabricio Coloccini are currently showing the level of commitment required to help Newcastle dig themselves out of trouble.
He told The Sun: "It is time the Newcastle players rolled up their sleeves and showed a bit of fight.
"It is fine wanting the ball and expressing yourself when things are going well — as they were last season. The real characters come to the fore when things are going wrong and, right now, this team does not have enough of them.
"With the exception of Fabricio Coloccini and Yohan Cabaye, everyone is hiding. This is a real relegation fight they are in, have no doubts about that. And it needs some big characters to get out of it."
Newcastle have a week off from Premier League action before a trip to face relegation rivals Aston Villa on Tuesday, January 29.