Clutha Health First manager Ray Anton said the GP practice had not been profitable for some time, and steps were being taken to stop it "bleeding money".
Mr Anton did not think it was appropriate to comment on how much the business was losing, but said it had not been producing a surplus for some time.
As the result of a review of the general practice service, the operating hours would now be 9am to 6pm, Monday to Friday, totalling 45 hours each week.
It has been operating from 9am to 9pm, seven days a week, or 84 hours each week, meaning the practice will be reducing its service by 39 hours.
The new hours take effect from Monday.
Patients seen after 6pm or during the weekends would be subject to an after-hours surcharge.
Now, patients seeing a doctor after hours pay a base rate of $32, with an after-hours surcharge of $18.
Mr Anton said this was still to be finalised.
Calls after 6pm and during weekends will be answered by ProCare, a private medical answering service staffed by nurses, and will be dealt with on a priority basis.
Mr Anton said the staff were at present rostered four days on, four days off, meaning patients were being seen by various different people.
The changes would also improve the clinical safety of patients, and would offer more attractive working hours to doctors, which would aid staff retention, he said.
