Liverpool say Gemma Bonner temporarily lost consciousness in an accidental clash of heads during Sunday's Women's Super League win at Manchester United.
The defender needed stitches and is now following WSL concussion protocols.
With the WSL entering a winter break after the weekend's fixtures, Liverpool will not play again until the FA Cup tie at Bristol City on 14 January.
"Gemma lost consciousness temporarily and suffered a facial laceration during the incident," Liverpool said on Monday.
"After treatment she was able to walk off the pitch with the assistance of medical staff and taken into the medical room at Leigh for further assessment.