A no-deal Brexit could “devastate” the NHS by disrupting the supply of life-saving medicine by up to six months, health leaders have warned.
The British Medical Association, Royal College of Nursing and the Royal College of Nursing are among organisations to join forces and issue the strong warning.
They said that leaving the EU without a deal could also intensify the staffing "crisis" in the NHS, adding that thousands of EU staff have already left since the 2016 referendum.
It comes after the Queen on Wednesday approved plans to prorogue Parliament following a request from Prime Minister Boris Johnson, meaning the time MPs have to pass laws to stop no-deal before the October 31 deadline would be cut.
In a joint statement, signed by 11 organisations also including the Royal College of Midwives, Unison, GMB, Unite and the TUC, health leaders called on the Government to take no-deal off the table.
The statement said: "A no-deal could cause significant disruption to the supply of medicine, lasting up to six months. Many medicines, including life-saving agents for cancer diagnosis and therapy, cannot be stockpiled and, for those that can, stockpiles could run out.
"These kinds of shortages and delays can be fatal. No responsible government should take that risk."
The union leaders also warned that leaving the EU without an agreement in place may worsen the staffing "crisis" in the health service. They said: "In the event of a no-deal, tens of thousands of NHS and care workers from the EU would be left in limbo, intensifying the largest staffing crisis in the service's history.
"Ministers must unequivocally guarantee the right of European health and care staff to continue to live and work in the UK.
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"Treasury assessments show that a no-deal scenario would shrink our economy by £90 billion, reducing the money available for the NHS and other vital public services.
"After a decade of austerity, health and social care budgets across the country are under immense pressure.
"With waiting times rising, operations being cancelled and yet another winter crisis looming, the health service cannot weather a long-term economic shock," said the statement.
Dave Prentis, general secretary of Unison, said: "Boris Johnson is setting a timebomb for the NHS. The promises of more cash for the health service made during the referendum were just empty words.
"No-deal will instead leave the NHS gasping for breath, creating chaos for the hard-working staff and disaster for patients."
A Government spokesman said: "As part of a responsible Government, the department is doing everything appropriate to prepare for Brexit.
"We want to reassure patients that we should be fully prepared for leaving on October 31 whatever the circumstances.
"We are taking all appropriate steps, meaning our plans should ensure the supply of medicines and medical products remains uninterrupted when we leave the EU.
"And we have been crystal clear that we want our hard-working EU staff to stay in the UK and continue to perform vital roles across the NHS and social care sector."
He added: "We've also recently committed £1.8 billion for the NHS, including funding for new hospital upgrades, and the record healthcare funding increases will continue following Brexit, most notably the extra £33.9 billion every year by 2023-24 through the NHS Long Term Plan."
Mrs Johnson asked to temporarily close down the Commons from the second week of September until October 14, when there will be a Queen's Speech to open a new session of Parliament.
The PM spoke to the Queen yesterday morning to request the end to the current parliamentary session in the second sitting week in September.
A Privy Council meeting was held at Balmoral to sign off Mr Johnson's plan, with Parliament now to be suspended no earlier than September 9 and no later than September 12.
Sources said Commons Leader Jacob Rees-Mogg, who is Lord President of the Council, Lords Leader Baroness Evans and Chief Whip Mark Spencer attended the meeting with the Queen.
The move from the PM has sparked outrage and opposition leaders have written to the monarch in protest. Commons Speaker John Bercow said the move was a "constitutional outrage" designed to stop Parliament debating Brexit.
The Prime Minister has called it "completely untrue" to suggest that Brexit was the reason for his decision.
He insisted he needs a Queen's Speech to set out a "very exciting agenda" of domestic policy.
"There will be ample time on both sides of that crucial October 17 summit, ample time in Parliament for MPs to debate the EU, to debate Brexit, and all the other issues," Mr Johnson said.
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