Charity shops are being left desperately short of stock as donations fall due to the deepening recession.
As more and more people choose to save their money by not buying new clothes, so they are continuing to wear what in normal times would be their cast-offs.
At the same time they are turning to charity shops to pick up a bargain, meaning clothing racks and shelves are becoming sparse.
David Moir, head of policy at the Association of Charity Shops, told The Daily Telegraph the problem of falling donations was "widespread".
"We are hearing very similar stories from across the country," he said.
He described the reason for the drop in donations as a case of "sheer economics".
"People are buying fewer new goods. It's as simple as that."
British charity shops turned over £120 million last year, he added, with almost two-thirds of that coming from clothing.
A ton of clothing can sell in a shop for £2,500 to £4,000, he added, producing a profit of £500 to £800.
Charities are now concerned their bottom lines could be affected by the downturn as supplies run dry, with many pleading for people to donate.
Ken Blair, chief executive of the British Heart Foundation, which has over 570 shops, said household collections had dropped by up to a quarter in the last year. All charity shops were suffering, he said.
"We are running desperately short of stock," he added.
Part of the problem was the increased demand for textiles from Asia, Africa and Eastern Europe, which has caused the price per ton to double from £400 to £800 since 2006.
Consequently more and more private companies have begun canvassing for used clothes from people's homes.
This has forced charities to spend more on obtaining decent supplies, Mr Blair said.
"The more we can get the public to support well-known charities at the moment the better," he commented.
Sales were "touch and go", he said, with the availability of stock being the key factor.
Shops with enough were doing well as people flocked to them to save money, he said. But he added that the issue was troubling the board.
"So far sales have been okay but I would not like to speculate what's going to happen," he said.
Cancer Research UK is urging people to "Detox your wardrobe", enlisting the help of television presenter Lorraine Kelly to get the message home.
She said: "We all know that times are tough, but this is an easy way to help raise money for charity."
Simon Ledsham, the charity's trading director, said: "Our shops are struggling to keep up with demand and are desperate for people to bring in good quality items that can be resold to raise money for the charity's important work."
Gordon Lishman, director general of Age Concern England, added: "While sales are up in our shops, donations of clothing, books and bric-a-brac have fallen by a fifth."