Greenwood clashed heads with Belgium's Jassina Blom in the 19th minute of England's 3-2 loss and was treated on the pitch for 12 minutes before her removal on a stretcher. Blom continued playing with a head bandage.
"Alex Greenwood will return to the City Football Academy for further medical assessments after sustaining a head injury on international duty," City said in a statement.
"We can confirm she has been carefully monitored, is alert and well and will return home later today ahead of a review with our medical team."
After the game in Leuven, England manager Sarina Wiegman gave an update on Greenwood's condition.
"She's fine, I haven't spoken to her yet. I also haven't spoken to the doctor yet, but I heard she's walking around," Wiegman said.
"Obviously she has a concussion, but it's good news that she's walking around and doing fine."
Manchester City, who lead the Women's Super League after four games, travel to Arsenal on Sunday.
