Striking nurses are marching with supporters to Downing Street as further mass walkouts of NHS were announced for the coming weeks.
In a message to the prime minister, nursing leaders said: "If you want to continue to have strikes ... that's exactly what you will get."
Nurses and ambulance workers are set to strike on the same day next month as the pay dispute with the government shows no signs of reaching a resolution.
The escalation comes as thousands of nurses walkout today and tomorrow at more than 55 NHS trusts in England.
Earlier, Steve Barclay, the health secretary, claimed that patients would pay the price if nurses got a pay hike.
Writing exclusively forThe Independent, Mr Barclay said any boost to wages would “take billions of pounds away from where we need it most”.
He wrote: “Unaffordable pay hikes will mean cutting patient care and stoking the inflation that would make us all poorer.”
