The veteran goal keeper will not return for training until the end of July, as per rules on rest periods after major tournaments, but the club wanted to assess an injury he picked up at the 2026 FIFA World Cup.
A frustrated Courtois was forced off in the closing stages of Belgium's 2-1 quarterfinal loss to Spain due to a hip issue.
Courtois' replacement Senne Lammens fumbled a save to gift Mikel Merino the winning goal for Spain in what could be end of the former's World Cup career.
The 34-year-old has set out his plan to take a break from Belgium duty, but return for UEFA Euro 2028 qualifying next year, and his injury scare is not expected to block him from starting the 2026/27 campaign in Madrid.
As per Marca, tests on Courtois' hip revealed no serious damage, and the former Atletico Madrid stopper will now head off on holiday.
Jose Mourinho is working with a limited squad this month, due to World Cup absentees, with Real Madrid starting their preseason match schedule against neighbours Leganes on July 28.