Guimaraes suffered a hamstring injury last week during a 2-1 victory at Tottenham.
He is now at home receiving treatment at his former club Atletico Mineiro. ChronicleLive reports that the decision was made between Newcastle and the Brazilian Football Confederation.
Guimaraes is being treated by his former club doctor Rodrigo Lasmar at the Cidade do Galo complex in Brazil.
Brazilian media sources say the injury was a "grade three tear" and Guimaraes narrowly avoided needing surgery. He will spend a month in Brazil.
Atletico Mineiro posted on social media yesterday: "He knows what’s best for him!
"Bruno Guimarães continues his injury treatment at Cidade do Galo. Under the supervision of Dr. Rodrigo Lasmar and with the support of the best medical department among Brazilian clubs, the player is preparing to return to the pitch in the best possible way! May you be back on the field soon, Bruno!"