Nearly four out of 10 carers spend more than 100 hours a week looking after their loved one, leaving some feeling isolated and lacking practical help, a major poll has found.
The survey of almost 57,400 carers for the Health and Social Care Information Centre (HSCIC) found 15% were unable to do anything they valued or enjoyed due to their caring responsibilities.
When asked to rate their satisfaction with support and services received in the last 12 months, 15% were extremely satisfied, 26% were very satisfied, and 33% were quite satisfied.
Some 6% were quite dissatisfied, 3% were very dissatisfied and 3% were extremely dissatisfied, all up on the previous survey.
Overall, 38% of carers said they spent 100 hours or more per week looking after the person they cared for, up on the 36% in 2012/13.
About 20% said they had freedom to spend their time as they wanted, down from 22% previously.
Some 15% did not get chance to enjoy anything, while 65% got to do some of the things they liked.
Fewer people than in 2012/13 said they had total control over their lives. Some 61% said they had some control but not enough.
The report, the Personal Social Services Survey of Adult Carers in England, covers carers known to local authorities.
HSCIC statistician Katharine Robbins said:"This survey helps lift the lid on the lives of the many thousands of people who care for another adult as part of their everyday life.
"It shows a wide range of experiences of carers known to local authorities."
When asked to consider the encouragement and support they received in regard to their caring role, 40% of carers felt they had encouragement and support, while 17% felt they had none.
Some 15% neglected themselves in terms of eating well or getting enough sleep, up on 14% previously.
Just over a quarter (28%) said they could not look after themselves some of the time.
Helena Herklots, chief executive of Carers UK, said: "The results of this year's survey reflect what we know from families; that they are providing more care with less support and are finding it harder to look after their own health, maintain relationships with others and have a life of their own alongside caring.
"Carers save the economy £119 billion every year in the unpaid care they provide, yet their own health and wellbeing is suffering.
"As the Treasury finalises the spending review, the results of the survey should be a wake-up call for national and local government that more funding is needed for support to back-up carers."
Charlotte Argyle, carers programme manager at Macmillan Cancer Support, said: "It is worrying that carers are neglecting their own health and that thousands aren't getting enough support.
"Carers who are not supported can reach crisis point or have a breakdown.
"As well as being extremely distressing for carers, this can affect the health and wellbeing of the person they're looking after.
"We know this can lead to unplanned hospital admissions for someone with cancer, or the carer, as well as an increased reliance on health and social care services if the family member or friend is unable to continue caring."
Caroline Abrahams, charity director at Age UK, said: "Most carers care willingly but the fact remains that caring is often a tough and relentless job which exacts a considerable toll on the carer.
"In addition, older carers - of whom there are growing numbers - may well have their own health and care needs too, which they sometimes neglect because they are too busy to seek help."