Private renting is making millions of people ill with almost half of England’s 8.5 million renters experiencing stress or anxiety and a quarter made physically sick as a result of their housing, campaigners have said.

Unaffordable rents, poor living conditions and the risk of eviction are causing a quarter of people – about 2.7 million – to feel hopeless while more than 2 million have been made physically ill, according to polling of nearly 4,000 private renters on behalf of housing charity Shelter.

The snapshot comes as families increasingly rely on private renting as the cost of ownership rises out of reach. A quarter of families in England rent privately, nearly 1.6 million last year, more than double the number recorded in the government’s English housing survey a decade earlier.

The poll, taken by YouGov in August and September, suggested a third of renters had lost sleep at night because of worries in the last year.

“Every day at Shelter we see the toll that expensive, unstable or poor-quality private renting can take on people’s lives and their health,” said Andrea Deakin, the charity’s emergency helpline manager. “We know how easy it can be to lose hope and feel overwhelmed by these worries, but our message is that you do not have to face them alone.”

Claire, 41, a renter in Poole, Dorset, said the twin problems of fighting an eviction notice and trying to persuade the landlord to get repairs done left her “in a mess and couldn’t function properly”.

“The worst bit was when I was trying to get them to fix my kitchen,” she said. “Cupboard doors would come off in my hands when I was trying to open them. I’d ask [the landlord] to have a look at it and they’d just say ‘It’s fine, it’s still functional’. How can you expect people to live like that?”

Dani Wijesinghe, an organiser for the Bristol branch of the community union Acorn, said: “It is the rule rather than the exception [for tenants she represents] to be experiencing illness: most commonly anxiety, depression, and respiratory conditions.”

Landlords dismissed the findings as “stoking needless fears” and accused Shelter of “giving the false impression that landlords spend all their time looking for ways to evict their tenants or increase their rents”.

In response, David Smith, the policy director for the Residential Landlords Association, said: “Not all landlords are perfect but the objective assessment is that the overwhelming majority of private sector tenants are satisfied with their accommodation and enjoy a good relationship with their landlord.”

He cited government research that suggested 84% of private sector tenants were very or fairly satisfied.

Landlords have seen the value of their investments more than double over the last decade to £1.6tn, according to research published this week by Savills.

With fewer rented homes coming on to the market than the rise in new renters, the cost of lettings is forecast to rise by more than 3% a year over the next five years .

Renters on average spend 41% of their income on housing costs, more than any other tenure, official figures show.

Polly Neate, Shelter’s chief executive, said: “A whole generation of children risk growing up surrounded by this constant stress and anxiety. This cannot go on.

“In the Queen’s speech, the government announced the renters’ reform bill, a once in a generation chance to rebalance the power between renters and their landlords, and make renting fairer … We see a lot of promise in these reforms, and look forward to working with the government to ensure that real and ambitious change is achieved.”

Ministers pledged to bring an end to “no-fault” evictions, which allows landlords to give tenants just two months notice even if they have done nothing wrong.

A tougher challenge will be improving the poor quality of a large minority of rented homes, with one in seven shown by the government’s English housing survey to contain a health and safety hazard.