In a drastic step to try to free up hospital staff and beds, NHS England has urged hospitals to defer day-case procedures and routine outpatient appointments until January 31.
To help free up doctors for patients with the most urgent need, the body also said the deferral of non-urgent inpatient elective care - such as hip replacements - should be extended until January 31.
Officials have estimated that this could lead to up to 55,000 deferred operations.
Cancer operations and time-critical procedures should go ahead as planned, NHS England said.
The move comes after leading medics warned that every emergency department in the country is struggling to cope with winter pressures.
Some hospitals have declared themselves at the most severe pressure level while doctors warned that scores are operating at almost full capacity.
Meanwhile a number of ambulance services are also under severe pressure, with two even resorting to taxis to ferry patients to hospital.
NHS England hopes the measures will free up senior hospital doctors to triage more patients in A&E, be available for phone advice for GPs and ensure that patients in hospitals are reviewed twice each day to help timely discharges.
It also announced that sanctions for mixed sex accommodation breaches should be temporarily lifted.
Under NHS rules m en and women are supposed to be treated on different wards and breaches can lead to fines.
But trusts can now breach the rules without being penalised.
The measures from the health body were announced following a meeting of its National Emergency Pressures Panel, chaired by Professor Sir Bruce Keogh.
In a statement, NHS England said that the panel discussed "sustained pressure over the Christmas period" with high levels of respiratory illness, high bed occupancy levels, signs of increased flu activity and a rise in the number of severe cases attending A&E.
Sir Bruce, NHS England national medical director, said: "I want to thank NHS staff who have worked incredibly hard under sustained pressure to take care of patients over the Christmas.
"We expect these pressures to continue and there are early signs of increased flu prevalence.
"The NHS needs to take further action to increase capacity and minimise disruptive last-minute cancellations. That is why we are making these further recommendations."
A number of hospital trusts have declared Operational Pressures Escalation Level 4 (OPEL4) which means they are unable to deliver comprehensive care and patient care and safety could be compromised."
The RCEM and the Society for Acute Medicine both issued stark warnings over pressure.
Emergency medicine consultant Dr Adrian Boyle, chairman for quality at the RCEM, said: "Everybody is struggling at the moment".
He said: "Every type 1 emergency department that I know of is under serious and sustained pressure.
"It feels worse than the equivalent period last year.
"This means that ambulances are waiting outside emergency departments waiting to offload, the emergency departments are full, clinical staff are working extremely hard to try and look after these patients, often having to treat patients in corridors, people suffering lengthy delays.
"And we know that excessive crowding within emergency departments is associated with avoidable deaths."
Dr Nick Scriven, president of the Society for Acute Medicine, added: "The position at the moment is as bad as I've ever known.
"Pre-Christmas 43 trusts were more than 98 per cent full despite 3,000 extra beds in use. I expect this to be at least doubled, maybe trebled today.
"We are starting to report Australasian flu is beginning to appear which is worrying. We are seeing a lot of flu-like symptoms but as yet do not know if it is 'normal' or the Australasian strain."
Jonathan Ashworth, Labour's shadow health secretary, said: "Despite the heroic efforts of our fantastic NHS staff, Theresa May's reassurances have proved meaningless and hollow. Tory underfunding and cuts have left our health service more vulnerable than ever before.
"What's more, the suspension of sanctions for mixed sex accommodation breaches is just one more humiliating indication of just how shocking the downturn has become.
"As the NHS enters its 70th year, the truth is that Tory neglect has left it underfunded, understaffed and overstretched. Ministers must get an urgent grip of this escalating crisis."