The victim was attacked by another woman on a Blackpool North rail service on Tuesday morning (April 5).
The woman reportedly kicked the victim in the face before alighting at Kirkham and Wesham railway station.
Officers from British Transport Police met the train at Preston railway station.
Police said enquiries into the incident were ongoing.
If you have witnessed or been the victim of crime, report it by calling 101 or visiting www.btp.police.uk/reportcrime.