More than eight out of 10 unpaid carers say they have had "no respite" since the beginning of the pandemic, research indicates.
Pressures also hit care service workers - who support unpaid carers - with more than three quarters (76%) dealing with an increased workload since the beginning of last year, according to Carers Trust Scotland.
The charity said lockdowns and restrictions meant many unpaid carers could not split responsibilities with family or friends, compounded by supplementary support services either being stopped or scaled back.
Overall, more than 500 participants shared their experiences with researchers.
Some 90% of unpaid carers said they had spent more time caring since the beginning of the pandemic, while 82% said they had had no respite.
Some support workers also "highlighted the emotionally demanding calls from unpaid carers, and the challenges of taking these calls in a home working environment without the support of colleagues that you would have in an office", said the charity.
Carers Trust ambassador Professor Saul Becker said: "During the pandemic, unpaid carers of all ages have been spending more time caring and more people than ever before have taken on unpaid caring responsibilities while statutory and other support services have been reduced or not available.
"This has also added additional pressures on carer support services that have had to adapt their practices quickly and provide holistic support to unpaid carers during very challenging circumstances."
The report comes as Holyrood considers whether to double the Carer's Allowance Supplement given to unpaid carers at the end of the year, currently claimed by around 83,000 people.
The Parliament's Social Justice and Social Security Committee is considering increasing the £231.40 paid twice a year to unpaid carers by doubling it when it is awarded in December.
Mental wellbeing and social care minister Kevin Stewart said: "Carers and the services that support them have done a remarkable job in very difficult circumstances over this past year during the pandemic.
"During the pandemic, we have invested an additional £1.9 million in extra carer support via carer organisations.
"The Scottish Government continues to work closely with the Carers Trust and national care organisations to ensure that carers continue to receive the support and the services they rely on.
"We will continue to do so as we move into a new phase of the pandemic and society starts to open up."
There are estimated to be around 690,000 unpaid carers across Scotland, although the Scottish Government says about 83,000 are eligible for the allowance.