A report into the impact of mental health problems on personal finances has called on retailers and the financial industry to help fix the "toxic relationship".
Almost three quarters of people who have experienced a mental health problem said it had made their financial situation worse, and not just as a result of having less money to spend, the poll for the new policy institute Money and Mental Health, set up by MoneySavingExpert.com founder Martin Lewis, found.
Some 93% said they spend more when unwell and 92% said they found it harder to make financial decisions, while 59% had taken out a loan they would not otherwise have borrowed.
Of those who had taken out new credit in the last year, more than a third (38%) said their mental health at the time left them unable to remember what they had been told about the loan, the poll of more than 5,000 people found.
Three quarters of people (74%) put off paying bills when they are unwell, 71% avoid dealing with creditors and more than half (53%) have ended up seriously behind on payments for at least one bill or loan agreement.
Mr Lewis said he had been concerned about the problem "for many years", adding: "There are two taboos: people won't talk about money problems and they won't talk about mental health problems. The point of this is trying to break these taboos. The two feed off each other.
"Let's normalise this in a good way."
He said: "We know financial difficulties can have a serious detrimental impact on mental health, but this report now shows conclusively that it goes both ways - mental health problems can devastate our finances too.
"Our vision is of a world where mental health problems don't lead to financial difficulty, and where problems with money can be managed without long-term impacts on our mental health.
"To get there, we need the financial services industry, health and policy-makers to take this issue as seriously as we do with practical solutions. This is my personal call-to-arms for them to please join us and fix this toxic relationship for good."
The institute's director, Polly Mackenzie, said: "Some progress has been made in recent years to improve how people with mental health problems are treated once they are in debt, but little attention has been given to preventing this happening in the first place.
"The financial services and retail industries need to recognise that a quarter of their consumers have a mental health problem every year - and they may need extra support or protection to stay financially healthy.
"People with mental health problems do not deserve to be written off to a life of financial difficulty."