Carers in Scotland are "reaching breaking point" as they struggle to take even a day away from their responsibilities for years at a time, research has found.
Carers UK surveyed 648 unpaid carers in Scotland and 22% said they had not had one day away from caring in five years.
The charity has called for immediate action, including more funding ring-fenced to ensure breaks for carers.
Ministers said new legislation was designed to support carers' well-being.
A Scottish government spokesman said the Carers (Scotland) Act due to be introduced in April next year includes "a duty on local authorities to provide support to carers who meet the local eligibility criteria and to consider whether a break from caring is required".
The survey by Carers UK came as new figures from the Office for National Statistics (ONS) showed that 8% of the UK private household population are informal carers for another person.
The Carers UK study found that more than a third (35%) had not had a break in more than a year and, of these, about three-quarters reported a deterioration in their health, both mental (77%) and physical (71%).
Carers in Scotland said breaks were the top factor able to make a difference to their health and well-being but only 16% were currently accessing them through services such as respite or alternative care.
'Enormous value of unpaid care'
The vast majority of carers (86%) said they "struggle" to take time away from caring duties, with the care needed not being on offer the largest reason behind the difficulty (29%).
More than a quarter (27%) reported the cost of a break as a barrier while the same percentage cited the person being cared for being unwilling to accept support from others.
Further obstacles to securing time away were low confidence in the quality of care and lack of awareness of how to request a break.
The charity said cuts to adult social care services were "fuelling growing anxiety" over the level of future support, with a third of carers in Scotland reporting a change in the services they received and, of these, 33% experiencing a reduction in the amount of support offered by social work services.
Carers Scotland director Simon Hodgson said: "More and more of us are stepping in to provide care and support to loved ones, and doing so for more hours every week.
"Without access to breaks, carers can quickly reach breaking point, unable to look after their own health, nurture relationships with friends and family or have the time they need to themselves.
"Our research shows that carers are struggling to get a break because appropriate support for their loved ones isn't available or services they rely on are being cut or charged for.
"Given the enormous value of unpaid care provided by Scotland's 759,000 carers, estimated to be worth over £10.8bn each year - getting some time away from caring to spend time with a partner, get to a medical appointment or just get a full night's sleep surely isn't too much to ask."
The Scottish government said it was "vitally important" to support Scotland's carers and young carers.
The spokesman added: "Increasing Carer's Allowance to the same level as Jobseeker's Allowance is a key commitment for our new social security powers which will start in Summer 2018 - an investment of more than £30m per year.
"More funding than ever before is being provided to support carers and young carers. Since 2007, we have invested over £130m in a range of programmes and initiatives, including over £20m for the voluntary-sector Short Breaks Fund administered by Shared Care Scotland and the Family Fund."