More than four in five GPs responding to the college's annual tracking survey said their workload increases through winter - and 73% feared workload would 'negatively affect their ability to provide care for their patients' in the months ahead.
RCGP Scotland leaders said they were 'extremely concerned' at the findings from the survey - which also revealed that 81% of GPs believe numbers of patients consulting general practice each winter are rising.
More than two in three GPs reported working longer hours than they are contracted for, while 28% said they were so stressed that they are unable to cope 'at least once or twice a week or more often'. More than half of respondents believed working in general practice would 'get worse' over the coming years - with 56% citing workload and demand as key factors.
The findings follow evidence from England of factors driving up pressure in general practice - with increased waits for hospital treatment forcing patients to seek additional appointments, rising numbers of patients per GP and huge demand for appointments - alongside the COVID-19 vaccination campaign.
Tayside GP and joint chair of RCGP Scotland Dr David Shackles said: 'The winter period always brings increased pressure for general practice, particularly with the added challenges of the COVID-19 pandemic, which has seen GPs and their teams working beyond capacity for months on end.
'GPs work incredibly hard in challenging circumstances to meet the demand from patients all year round, however it is clear from these survey findings that GPs simply do not have the capacity to take on any further workload increases, particularly when there are already significant staffing challenges.
'Traditionally, over the winter period, there is no doubt that GP workloads increase, and we are extremely concerned about the impact this is likely to have on practice staff who are already finding it difficult to cope this year. Staff are exhausted and under strain - that's why retaining our GP workforce is our biggest priority right now.'
The poll also found that nearly two in five GPs who responded expected to leave the profession within the next five years.
Dr Shackles added: 'We simply cannot afford to lose any more GPs than we already have. We continue to call for measures such as protected time for GPs and practice teams to come together during the working week to learn, collaborate and develop to help in the shorter term.'
Fellow joint chair Dr Chris Williams said: 'With winter looming, GPs and their teams are already bracing themselves for a particularly tough few months ahead and the cracks are already starting to show.
'Unfortunately, capacity issues and system-wide workforce shortages are also likely to impact patients trying to access services across the NHS.'
Dr Williams said the college was urging patients to consider options such as consulting a pharmacy or self-care before contacting a GP this winter - and to take up offers of COVID-19 and flu vaccination.