Poorer households are already in “impossible positions” due to rising energy bills and soaring inflation, the head of Citizens Advice has warned.

Dame Clare Moriarty said things were already very difficult for households which have seen benefits and wages fail to keep pace with rising prices, which will become worse as energy bills increase in October.

She warned that long-term issues faced the country as a result of people unable to afford food or heating.

Dame Clare said Citizens Advice had been contacted by someone who was so concerned about energy costs she was considering abandoning the use of her chair lift, instead living on one floor of her home – but her bathroom and kitchen were on different levels.

Another client had a long-term condition but was “too frightened” to turn on their heating, while rising prices in shops meant food banks were dealing with people who had not eaten for more than 24 hours.

At an event organised by the Resolution Foundation think tank, she urged the new prime minister to act as soon as they entered No 10. Liz Truss or Rishi Sunak will replace Boris Johnson on September 6.

“We’re seeing people with more problems and more complex problems, quite a lot of threatened homelessness at the moment,” she said.

“We’re seeing mental health issues, we’re seeing relationship breakdowns, we’re seeing domestic violence – a whole set of things which are not directly to do with people’s financial position but which are also very much related to it.

“We’re seeing people who are already in impossible situations. One of the local Citizens Advice (staff) talked about somebody who came in who has a chairlift, who is frightened to use the chairlift because of the amount of electricity it needs, so was therefore trying to work out whether she could live in either the top floor or the lower floor of a house, but the kitchen was on one floor and the bathroom was on another.

“People who are coming in and saying ‘even though I’ve got a chronic health condition and I need to keep warm, I’m going to sit in constant pain, because I’m too frightened to turn on the heating when the weather gets colder’.”

She warned: “People on lower incomes do not have the capacity to absorb what’s happening at the moment, let alone what’s coming in October.”

The energy price cap for domestic consumers is set to rise 80% in October, taking average annual bills from £1,971 to £3,549.

Dame Clare said the next prime minister will have to announce a support package that will “match the scale of the problem, we are talking about millions of people who are going to need help”.

“Whatever the Government comes up with, it’s got to be something that can be implemented quickly because already people will be seeing their direct debits go up from now – direct debits can go up ahead of the actual increase in the energy price cap.”

Warning of a long-term cost to the state if the problem was not addressed, she added: “We are building a huge health issue.

“Living in cold, damp, unheated houses is bad for your health. Not eating properly is bad for your health. Worrying about how you are going to cope is bad for your health.

“So there’s a whole set of things where we are storing up long-term issues.”