Hospitals in Adelaide are on the lookout for a teenager who has been posing as a doctor and even looking over patients’ notes.

The former St John Ambulance volunteer has been spotted on wards several times at the Royal Adelaide Hospital wearing a name badge and stethoscope, and even reading patient notes.

In one photo on Facebook, he even brags about being on a break while at work at the Royal Adelaide Hospital.

He has also been seen at Flinders Medical Centre, in Adelaide’s south, wearing scrubs and a lanyard.

All hospitals have been sent a photo of the teenager and security staff have been told to apprehend him if he returns.

“He just turns up and sort of walks around pretending to be a doctor,” SA Health Minister John Hill said.

"He walks around with a clipboard and just talks to people.

“We don’t know of any cases where he has had interaction, direct interaction with patients.

"This is not something we want in our hospitals, we would like to ensure it doesn't happen any further.

Police have spoken with the teenager at the Royal Adelaide Hospital, but say there is no evidence he has broken any laws.

But if he does make physical contact with a patient while posing as a doctor, he could be charged with assault.