Police say 18 year old Brittney Russell has been missing from the Blackpool Victoria Hospital since Tuesday.
Officers issued an appeal via Facebook, saying they were "becoming increasingly concerned" about Brittney's safety.
The 18 year old was last seen at Blackpool Victoria Hospital at around 6pm on Tuesday, July 2.
Britney is described as 5'5", of slim build, with above shoulder length hair, and a lip piercing.
Police are appealing for any information to help find Brittney, who was last seen wearing a hospital dressing gown, black tracksuit bottoms, and black trainers.
Anyone with information can call 101, quoting log reference 1130.