Coutinho suffered a hamstring injury in Saturday's defeat to Real Madrid despite completing the full game at Camp Nou.
Barca said a timescale for the former Liverpool man's return "depends on how the injury evolves", but Brazil's doctors have also now assessed the player.
Doctor Rodrigo Lasmar said in a statement that he believes "there is not enough time for the recovery of the player for his participation in the next two rounds of [2022 World Cup] qualifiers".
Should Coutinho be available for Barca again following the break, he would make his return against Atletico Madrid almost a month on from the initial issue.
Coutinho is set to be joined in missing Brazil's qualifiers by Liverpool's Fabinho. The midfielder, who has been playing in defence for the Reds since Virgil van Dijk's injury, sustained a hamstring problem in Tuesday's Champions League win over Midtjylland.
Liverpool were waiting for a scan on the injury on Wednesday, but Jurgen Klopp suggested Fabinho's absence would not represent a major blow for Brazil, as he has earned just 12 caps for his country and started on five occasions.
"I'm not sure if Tite's too worried because he plays him never, so he will probably now not sit on the bench for the next [two] international games," Klopp said.
He also told beIN SPORTS: "We have to wait for the scan obviously but you know these times when somebody is going off with a muscle problem, then it's really rare that the doctor calls me the next morning and says: 'False alarm, all fine, he can go again.'
"So it's now only about how long. That's all, and nowadays a week means three games, 10 days means four games, 14 days means seven games and all these kinds of things. So that's how it is. Yeah, absolutely not cool but that's the situation."