Patricia Marquis, director of the Royal College of Nursing (RCN) union in England, said the government must listen.
"This is not something that nurses do at the drop of a hat," she told Reuters.
But the RCN's Marquis said that without higher pay, staff would continue to leave the profession, increasing the pressure on those who remain and ultimately damaging patient care.
"But each time I've had the chance, I sort of had to pause for a minute and say 'I can't leave my patients.
I can't leave my colleagues to suffer alone'," he said.