Two in five unpaid carers put their own health at risk to look after a loved one, according to a survey.
Some 40 per cent of carers said they had put off seeking medical treatment because of the demands of caring for someone who was ill, frail or disabled, a survey of 3,400 unpaid carers found.
In addition, 87 per cent of carers said that caring for a loved one had been detrimental to their mental health, while 83 per cent said it had affected their physical health. Thirty six per cent of the carers questioned said they had sustained a physical injury such as back pain through looking after someone close to them.
The survey findings have been released at the start of Carers Week, organised by a group of eight charities including Age UK, Carers UK and Macmillan Cancer Support.
The charities called for better financial and practical support for the 6.4 million unpaid carers in the UK, so they can look after their health and well-being.
Many carers have delayed getting medical treatments ranging from a hernia operation to cancer screening as a result of their caring responsibilities, the charities said.
Tracy Sloan, 45 has cared for her son Phillip, who has severe cerebral palsy, for 20 years. Last year, she put off a regular screening appointment and then discovered she had cancer. Even after being treated, she said she had little time to recover.
"Looking after Phillip is so full on, that it just didn't occur to me to keep an eye on my own health.
"I was really shocked when I discovered I had cancer and needed an operation. I came home from hospital exhausted, emotional and fragile.
"I really needed the chance to rest but instead I had to deal with Phillip's demands too and that took its toll on my recovery."
Carers Week manager Helen Clarke said: "It's a scandal that carers can't get the time or support they need to look after themselves which could be jeopardising their health as a result.
"Carers are feeling the strain of a woefully underfunded system and still we're seeing more cuts. Unpaid carers save the Government a fortune - £119 billion a year, yet they're let down in return. It is time for urgent action to tackle the crisis in social care."