Health Minister Peter Dutton has flagged an overhaul of Medicare, warning soaring costs will make the system ''unmanageable'' without change.

In an interview with Fairfax Media, Mr Dutton gave the strongest signal yet that the Abbott government may adopt a politically explosive proposal to charge a $6 fee to visit the doctor.

While refusing to comment directly on the proposal, made by Tony Abbott's former policy adviser Terry Barnes in a submission to the Commission of Audit, Mr Dutton said Medicare Benefits Schedule spending had grown at a ''rapid'' rate over the past decade and some argued this growth was ''unsustainable''.

''In the end, we want to strengthen Medicare and we want to strengthen our health system, but we can't do that if we leave change to the 11th hour,'' Mr Dutton said. ''The threshold question is whether people want the health system of today strengthened for tomorrow, because at the moment the health system is heading to a point where it will become unmanageable.''