Hospital chiefs on Wednesday warned of the danger to patient safety by the latest doctors strike, the first time consultants and junior doctors in England have walked out at the same time.
The doctors and government are deadlocked over the medics' pay demands amid the biggest cost of living crisis in a generation.
The strikes over heavy workloads and below-inflation pay rises have seen many thousands of appointments and operations postponed and come on top of a vast pandemic backlog weighing down the state-run National Health Service.
Previous industrial action has seen consultants and junior doctors strike at different times, allowing them to cover for each other.
"Consultants and junior doctors walking out together is the awful scenario health leaders have long feared," said Matthew Taylor, chief executive of the NHS Confederation, which represents NHS organisations.
Taylor said that the strike could result in 100,000 operations and appointments being cancelled, taking the total to "well over a million" since the start of the long-running series of walkouts.
"Leaders will have pulled every lever available to them to mitigate the impact of this strike, but it is inevitable that patient safety is compromised," he said adding that the level of risk was the "highest we've seen for a long time".
A two-day strike by consultants started on Tuesday with junior doctors joining them for a three-day strike from Wednesday.
Further joint strikes by consultants and junior doctors are planned for October.
Consultants are pushing for an above-inflation pay award this year -- inflation was running at around 11 percent in April -- while junior doctors have asked for 35 percent.
UK Prime Minister Rishi Sunak, however, has told the doctors to call off their stoppages and warned that the government will no longer negotiate on higher salaries.
He has said the government had accepted recommendations from independent pay review bodies for salary increases of between 5.0 and 7.0 percent in the public sector.
The strikes are the sixth time junior doctors have walked since March. Consultants have now walked out three times since July.
They are just the latest group -- from train drivers to lawyers -- who have staged industrial action in the UK as inflation has soared, sending food, housing and other costs spiralling.
Nurses and ambulance staff have also taken strike action, eventually accepting a five-percent pay rise in May.
© Agence France-Presse