Scotland's hospitals are "almost completely full", with bed occupancy exceeding 95% last week, the first minister has said.
Nicola Sturgeon said services were facing "truly unprecedented" pressures.
Demand for hospital beds had been driven up by "extraordinary" levels of winter flu, rising rates of Covid infections and cases of Strep A.
Ms Sturgeon said more work needed to be done to prevent unnecessary hospital attendances and to speed up discharges.
Staffing of the NHS 24 helpline is to be increased, while health boards will be backed in maximising capacity by opening GP practices on Saturdays.
In a special briefing at the Scottish government's St Andrew's House headquarters, Ms Sturgeon said this was "almost certainly the most difficult winter ever for the NHS".
She said the pandemic had dealt a "significant shock to the system" and that this, coupled with "extraordinary levels of other illnesses", was creating unprecedented pressure.
More than 400 people with Covid-19 were admitted to hospital last week, on top of more than 1,000 patients with winter flu for the second week running.
Ms Sturgeon said there had been more than 100,000 calls to NHS 24 over the holiday period, the highest number in more than a decade.
Meanwhile the ambulance services responded to more than 16,000 emergency incidents in the past week, up 11% on the average for the previous four weeks.
On Wednesday last week, hospital bed occupancy exceeded 95% - compared to 87% in the same week in 2020.
Ms Sturgeon said hospitals were currently "almost completely full" and that more needed to be done to reduce "unnecessary attendances".
This will include an expansion of the NHS 24 helpline, with an acceleration of work on a new app and self-help guides.
Ms Sturgeon said services were also working on "other options for patients who do not need to be at accident and emergency".
The first minister added that more was being done to speed up the discharge of patients from hospital, with 1,700 people currently estimated to be stuck in hospitals.
Extra funds are being given to health and social care partnerships to book extra care home beds, with the goal of freeing up capacity on wards.
Health boards will also be given fresh guidance on the "escalation contingencies" they can take to protect "critical and life-saving care".
Opposition parties at Holyrood have called for the Scottish government to take responsibility for the difficulties facing services.
Both the Conservatives and Labour have demanded the resignation of Health Secretary Humza Yousaf, with the Tories saying he had "lost the confidence of NHS staff".
Labour's Jackie Baillie said Ms Sturgeon "needs to sack Humza Yousaf and appoint someone who is up to the job".
However, Ms Sturgeon insisted that the health secretary was "doing a very good job in very difficult circumstances".
Mr Yousaf said he was "working relentlessly, leaving no stone unturned to make sure I am providing as much support as I possibly can to the health service".
The first minister also said that "in a relative sense, NHS Scotland is dealing with some of these pressures in a better way than we would see elsewhere and some of the statistics bear that out".
Source: BBC
Image: The Times
