Linda Silas says some governments haven't adequately replaced retiring nurses because of budget cuts and too often use overtime as a crutch to fill staffing gaps.
"We are not learning and we are having a system that's living on overtime," Silas said in an interview.
Nova Scotia is among those provinces facing a shortfall with about 185 acute and long-term care nursing positions vacant.
The province's Liberal government was told when it came into power about 18 months ago that Nova Scotia could face a shortage of 800 nurses within five years if there was no change in a number of factors, such as the number of seats made available in nursing schools.
Silas said Nova Scotia is one of the first provinces to face a shortage of nurses.
"What's happening in Nova Scotia is just an early symptom of what's going to happen across the country," she said.
Long-term human resource planning is needed to reduce the effects to frontline care, which includes increased overtime and work absenteeism, Silas said.
Nurses worked more than 21 million hours of overtime in 2012 at a cost of more than $952 million to the health care system, Silas said, adding it's no coincidence nurses' sick time also increased.
A 2013 study for the national union reported that an average of 18,900 publicly employed nurses were absent from work each week in 2012 due to illness or injury.
Janet Hazelton, president of the Nova Scotia Nurses Union, said the shortage will continue in her province unless more is done to address overtime and high injury rates. Right now, she said there's little incentive for older nurses to stay in the system once they reach pensionable age because of the increased demands of the job.
"There are not many who are going to work between 56 and 60 (years of age) unless we can figure out a way to make them stay," said Hazelton.
A good start would be to hire above required needs to ensure staffing levels remain constant when nurses are off sick or book vacation time, she said.
But that appears unlikely with health spending increased just 0.8 per cent in Nova Scotia's latest budget, the smallest increase in a decade.
Cindy Cruickshank, director of health system workforce policies and programs for the Nova Scotia government, said there are 14,000 registered nurses, licensed practical nurses and nurse practitioners in Nova Scotia. That's about 2,000 more than in 2001 when the province released its first nursing strategy.
Department figures show that last year, 46 per cent of the province's registered nurses and 40 per cent of its licensed practical nurses were over the age of 50.
Cruickshank said 669 nurses left the system last year, while 662 were hired as replacements.
"Of the 669 that went out, approximately half of that was due to retirements just based on the age profile alone," said Cruickshank.
The province is only now seeing the results of a decision in 2008 to increase the number of seats in nursing schools from 330 to 401, said Cruickshank, and increased demand has seen the hiring in Nova Scotia of almost 90 per cent of graduates from the province's schools.
Still, she said challenges remain in attracting nurses to rural areas and in filling shortages in specialties, such as critical care and operating room programs.
A change in the province's nursing strategy that is expected next month will "target hard to fill areas," she added.
"We have to keep our pedal to the gas so to speak."