The 25-year-old has not been on the pitch since the start of August due to a back problem and then later a virus.
As a result, the playmaker has missed three Premier League games, as well as the Reds' Champions League qualifying win over Hoffenheim.
During that time, Coutinho has been heavily linked with a move to Barcelona, and even handed in a transfer request to force a deal, but the Spanish giants have reportedly had three bids rejected.
Despite the player's absence for Liverpool, Brazil national team doctor Rodrigo Lasmar has confirmed that Coutinho is fit enough to take part in his nation's matches this week.
"From a medical point of view, Philippe is in the perfect condition to play," the Liverpool Echo quotes Lasmar as saying.
Brazil will face Ecuador on Thursday evening before taking on Colombia in another World Cup qualifier five days later.