The former England international turned his ankle during the warm-up prior to Sunday's Championship clash with Charlton and left The Valley on crutches.
He was replaced by youngster Lee Nicholls, who impressed on his league debut with a clean sheet in the 0-0 draw and is set to keep his place against QPR on Wednesday.
Coyle confirmed the news of Carson's injury at his pre-match press conference.
"Scott Carson's scan showed an ankle strain, he'll be out for a number of weeks," he said. "He's been excellent for us so it's a big blow.
"Lee Nicholls will play (Wednesday) night and he's going to go from strength to strength. He was excellent on Sunday."
- Sports & Recreation
- Scott Carson
- Lee Nicholls