Nurses are working the equivalent of one day a week for nothing, according to a study.
Researchers from London Economics were commissioned by the Royal College of Nursing (RCN) to look at pay in England, Wales, Scotland and Northern Ireland since 2010.
They found that the salary of an experienced nurse had fallen by 20% in real terms, based on a five-day week.
Experienced nurses in England, Wales, and Northern Ireland would need a nominal pay rise of 45% by 2024-25 just to return their salaries to levels seen in 2010-11 in real terms, the research said.
And such a pay rise would actually help the NHS save money in the long term, as it would be cheaper than hiring staff from overseas, according to the study.
Dr Gavan Conlon, who oversaw the research, said that bringing staff in from overseas costs approximately £16,900 more annually than retaining a nurse, while using agency workers costs around £21,300 more per year.
He said that about 32,000 nurses leave the NHS every year, many due to the failure of their pay to keep up with the rising cost of living.
The RCN is balloting its 300,000 members for strike action, calling for higher pay and an effort by government to fill the hundreds of thousands of nursing vacancies across the country.
There are also strike ballots under way or expected for midwives and other NHS staff such as porters, paramedics and cleaners.
The RCN's general secretary Pat Cullen said: "This exploitation of nursing staff cannot be tolerated any longer.
"In the pandemic, the politicians urged the public to clap for carers, but now they are wilfully ignoring nursing's astonishing efforts and expertise.
"Ministers have stubbornly resisted the requirement to address the workforce crisis, including paying nursing fairly, instead rejecting any opportunity to act.
"They have taken advantage of nursing's goodwill and steadfast determination to act in the interests of their patients.
"Our members have had enough.
"Expecting nursing staff to work one day a week for free is totally unacceptable.
"Patients deserve better from their politicians.
"Despite nursing staff working increasingly long hours and doing all they can, safe and effective care is being undermined by the failure of governments to act."
A Department of Health and Social Care spokesperson said: "We hugely value the contribution of our hardworking nurses, which is why we are giving over one million NHS workers a pay rise of at least £1,400 this year.
"NHS staff also received a 3% pay rise last year, increasing nurses' pay by £1,000 on average, despite a public sector pay freeze."