Symptoms of ignoring the problem – and not making the debt go away – include not opening bills, or hiding the extent of the financial crisis from family.
Stephen Rose, director of the Debt Advice Bureau, said: “There is nothing wrong with borrowing but racking up mountains and mountains of debt to subsidise a lifestyle you can’t afford: that’s what the problem is.
“There is a small group of people who are completely in denial about their debt situation, people who typically put the red letters in a drawer and don’t open them.”
His warnings come as total UK debt surpasses £1.1 trillion but borrowing continues.
Mr Rose called on people to stop living in denial about the extent of the problem and do something to clear debt.
With young people the most likely to deny they have a problem, he urged consumers to face up to debt and take advice so that it can be tackled rather than build up.