Patients across Tayside face delayed operations because hospital beds are filled with an increasing number of winter virus sufferers.
NHS Tayside has been forced to cancel a number of non-emergency procedures as a result of the outbreak, which has worsened since first striking before Christmas.
The health board said hospitals were experiencing exceptional demand for services and the issues could continue for months.
The board has assured people emergency and urgent cases will be unaffected but apologised for the distress caused by rescheduling operations.
One man, who asked not to be named, told The Courier he had been in pain for four months as a result of a hernia and had been desperate for treatment.
He now faces a further 12-week wait for a rescheduled appointment, having been told his operation had been put off hours before he was due at Ninewells.
He said: “I know they may have difficulties, but I do feel that if people are waiting to be seen then they should be seen.”
A spokeswoman for NHS Tayside said the decision to defer procedures had been taken as a last resort, given “the distress it will have caused to patients and their families”.
She said: “Over the last few days we have been experiencing exceptional demand on our system as we manage winter pressures.
“There has been a significant increase in the number of patients admitted into our hospitals from the community with viral illnesses, including respiratory conditions, with many patients acutely ill.
“This is having a significant impact on the number of beds available and, unfortunately, this higher than normal number of unscheduled admissions has also had a knock-on effect on our ability to deliver routine procedures.
“We have had to defer a small number of non-urgent, elective procedures across Tayside.
“Emergency and urgent surgeries and all cancer procedures have been carried out as scheduled.”
NHS Tayside is now in the process of contacting patients again to arrange suitable alternative dates for their procedures.
In Fife, NHS bosses said the numbers of patients presenting with winter virus conditions was “broadly in line” with what would normally be expected at this time of year.
Interim director of acute services, Professor Scott McLean, said services “continued to cope well, with all elective activity taking place as planned”.