Junior doctors are on strike from Wednesday 3 January until 7am on Tuesday 9 January, making this the longest consecutive strike action ever taken in the history of the NHS.
The NHS has warned of significant impact on all routine care, with urgent and emergency cases being prioritised.
The strike comes in the middle of winter, when the NHS is already under pressure from winter illnesses like covid and flu.
Most recent data shows that people in hospital with flu has jumped to an average of 942 each day last week – almost six times the number compared to the week before.
NHS National Medical Director Professor Sir Stephen Powis said: “This January could be one of the most difficult starts to the year the NHS has ever faced.
“Six consecutive days of industrial action comes at one of our busiest periods – the action will not only have an enormous impact on planned care, but comes on top of a host of seasonal pressures such as covid, flu, and staff absences due to sickness – all of which is impacting on how patients flow through hospitals.
“Our colleagues across the health service are doing their very best for patients every day with extensive preparations in place, but there’s no doubt they are starting 2024 on the back foot – not only will action impact next week, it will continue to have a serious impact in the weeks after, as we recover services and deal with additional demand.
“However, I cannot stress enough that people who need care must come forward as they usually would – using 999 and A&E in life threatening emergencies and 111 online for everything else.”
The BMA said: "The Government has taken a stance that strikes must be called off for it to resume negotiations – while the BMA has consistently said it will resume talks at any time.
"When the Government failed to make a credible offer by the mutually agreed deadline in early December, this round of action – as well as three strike days before Christmas – were called.
"More than four weeks have passed since that deadline, with the Government refusing to make its ‘final offer’, which health secretary Victoria Atkins has said is still up her sleeve."