NHS Lothian has halted non-urgent elective operations amid staff shortages and rising patient demand.
The health board has also postponed non-urgent outpatient appointments.
The move comes two days after NHS Borders cancelled all scheduled routine operations until the end of next week due to pressure on services.
NHS Lothian said increased levels of staff sickness, combined with holidays and those having to self isolate, led to a “significant reduction” in nurses and midwives in the previous two months.
This, along with “unprecedented demand” has caused longer waiting times, particularly in the emergency department.
This is behind the decision to postpone procedures to enable clinic and theatre staff to be redeployed where they are most needed.
Other measures taken to address staffing problems include offering staff more shifts, and bringing in around 460 new nurses who are expected to start in the next two months as well as extra administration and domestic support.
Professor Alex McMahon, nurse director, NHS Lothian, said: “We are doing everything possible to mitigate the additional pressures we are facing, however we have to be realistic. These challenges will not disappear overnight.
“We continue to work through appointments that have already been re-scheduled in recent months and to see people who may have delayed seeking treatment because of Covid-19. This will take time.
“We also continue to be restricted in the number of people we can see each day because of the enhanced infection control measures in place. Covid is still with us.”
He urged people to help support the NHS by calling NHS 24 on 111 if they think they either need to visit a minor injury unit or visit A&E for a non life-threatening reason, so they can be directed to the right service.
He stressed that in an emergency people should dial 999 or go to their local A&E department.
Prof McMahon added: “The measures we have put in place over recent weeks are absolutely essential to allow us to continue to provide safe and effective patient care and we are urging everyone to work with us and support us as we move through this new phase.
“Our staff have been working on the front line since the start of the pandemic and we cannot praise and thank them enough for the ways that they are continuing to rise to every challenge placed in front of them.
“We are also really grateful to everyone in Lothian for their continued support and patience.”
On Wednesday, NHS Borders announced it would cancel all scheduled routine operations for the rest of the week and next week citing pressure on services.
“There is very high demand for in-patient beds, including rising numbers of patients who are being admitted with Covid-19,” the health board said.
“We fully recognise the distress caused by this unavoidable decision and are truly sorry.”