Marie Curie and Macmillan Cancer Support are urging early identification of people caring for those at the end of their lives.
A report from the charities spoke to bereaved people who gave palliative care to relatives and found early provision of information and support was vital.
The report found many carers were not identified as such and recommended all healthcare staff - but particularly GPs and district nurses - to do more to remedy this.
Other recommendations include speedy assessments and support plans for palliative carers, readily available respite care, and the carer’s details forming part of key medical information.
The report said there are “many missed opportunities” in end-of-life care.
“Ensuring that those caring for someone in the last six months of life gets the support they need as quickly as possible is crucial if they are to effectively carry out the caring role they have taken on,” it continued.
“A lack of support leaves both the carer and the cared-for person at risk of a breakdown in the care provided, which may lead to much greater complexities in the care provision needed, and quality of life available to the cared-for person and carer, beyond death and into bereavement.”
Health and social care workers should move towards presumption that a patient has a carer and to ensuring they are aware of their entitlements, it added.
Janice Preston, head of services for Macmillan in Scotland, said: “For the people that are caring for family members it is vital that they are getting the support they need.
“However, at the moment the current system is a pressure cooker and unless action is taken the consequences will fall heaviest on those carers.
“The wider health and social care system has a huge role to play in spotting and signposting cancer carers to get the help they need at the most difficult moments of caring.”
Richard Meade, head of policy and public affairs in Scotland for Marie Curie, added: “Caring for someone with a terminal illness can be all encompassing and too many carers are missing out on the support they need.
“New Adult Carer Support Plans provide us with a great opportunity to identify earlier family members, friends and neighbours who are caring and to put in place support quickly. It is everyone’s responsibility to ensure that carers are identified, and we are urging all health and social care practitioners to ask the person who is caring what support they might need.”