Police have launched an appeal for witnesses to the attack in the early hours of Monday, May 7, in York to come forward.
They said the 19-year-old, from Pocklington, needed hospital treatment after being attacked at around 3.20am in KUDA nightclub on Clifford Street.
North Yorkshire Police want to identify two suspects.
A police spokesperson said: "One was described as white, slim build, short, possibly dark hair and he was wearing a light coloured shirt.
"A second man, also white, was believed have also assaulted the victim but no further details are known about him at this time."