Dr Neil Dewhurst, who stands down this week as the president of the Royal College Of Physicians Of Edinburgh, also said the number of hospital beds being occupied now "commonly exceeds" what is regarded as the maximum safe level.
He said occupancy rates in some areas had reached as high as 124% last year as he said it was "essential" for the health service to commit to having a maximum occupancy rate of 85%.
The consultant cardiologist went on to call for "more stringent standards" for the quality of care to be brought in, as happened in England following the problems identified in Mid Staffordshire.
While Dr Dewhurst stressed there was "much to be proud of in the NHS in Scotland", he added that in recent years "a variety of pressures have built up in our hospitals that are now seriously impacting upon our ability to deliver the quality of care patients require".
He said problems in the health service had most recently been seen in NHS Lanarkshire, which was last year told a range of improvements must be made at three hospitals following a review into patient safety prompted by higher than average mortality rates. But he said these problems "could just as easily have happened" elsewhere.
Dr Dewhurst said: "Reductions in the numbers of acute beds while medical admissions have continued to rise, in parallel with workforce shortages, have placed almost intolerable pressure on our doctors and nurses."
The NHS has deployed a number of "coping strategies" to deal with this, he said, but he added that while these were "only ever intended as crisis management tools", they were now "in real danger of becoming accepted daily practice".
He said the practice of moving patients between wards because of overcrowding - known as boarding - was "only intended for times of severe pressure, such as during ward closures and outbreaks of norovirus or flu".
But he said this had now become "established practice in many Scottish hospitals on a year-round basis".
He went on to warn that the occupancy rate for hospital beds in Scotland "now commonly exceeds 85% nationally", with Dr Dewhurst saying evidence had shown this was "the maximum safe level at which we can treat patients".
He said: "Above this level, the risk to patient safety also increases. I believe it essential we commit to the UK-wide adoption of a maximum ward capacity of 85%."
A Scottish Government spokesman said: "Health resources in Scotland are at a record high of £11.8 billion. By 2015-16, there will be an increase in resource spending of £2.1bn since 2007.
"We have some of the safest hospitals in the world thanks to our Patient Safety Programme, which the UK Government is only now realising the value of.
"We are ensuring we have the right number of staff in the right place at the right time. Under this Government, NHS staffing is up 5.6%, with more than 1000 extra qualified nurses and more than 2000 more doctors and dentists since 2006.
"Each board now has a local unscheduled care plan that describes how services will be established, evolved and redesigned to better meet requirements of unscheduled care patients. This is tied closely to our work on boarding, which is being taken forward in close partnership with Dr Dewhurst.
"Indeed, we are the first country in the UK to take on this issue directly to ensure patients do not end up on wards inappropriate for their treatment."