An estimated 1.5 million such loans worth around £120bn are due for repayment in the next decade but with lenders much stricter about their lending criteria, there are fears that many will struggle to find another deal.
A string of lenders recently slashed the amount which can be borrowed on an interest-only mortgage to just 50pc of the home's value and in future this type of mortgage is set to be considered a "niche" part of the market, offered only to those who can clearly show how they will repay the capital.
Ray Boulger, senior technical manager at mortgage adviser John Charcol, said those on an interest-only mortgage will be "in the most difficult position" as lending rules tighten and for many, another deal with their existing lender could be their "only option".
Interest-only mortgages allowed borrowers to only pay off the capital when the mortgage term ended, enabling them to maximise their borrowing capacity at a time when property prices were outpacing wage increases.
The last property price boom fuelled a new surge in interest-only mortgages, peaking at a third of all mortgage sales in 2007.
According to the Council of Mortgage Lenders, more than 95pc of first-time buyers have been taking out repayment loans since the summer of 2011 and the proportion of repayment loans taken out by home-movers and those remortgaging has also been rising.
Under the Financial Services Authority's plans to clamp down on irresponsible lending, interest-only mortgages will only be offered in future where there is a credible plan to repay the capital, and borrowers cannot just rely on hopes that house prices will rise.
Mr Boulger said: "It may be that they can afford to switch to a repayment mortgage. People aged in their Fifties may find they can only get a mortgage for 15 to 20 years, perhaps 10 years."
He said that some borrowers could also try going for a compromise solution, as a small number of lenders offer mortgages which are part interest-only and part repayment.
"The options are going to be limited," he said. "At least one lender is changing their criteria a week at the moment."
Several lenders recently increased their number of higher loan-to-value mortgages, something borrowers might have had difficulty finding a year ago, which may help those with lower deposits.
Research from Moneyfacts found that the number of mortgage products offering maximum loan-to-values of 95pc has more than doubled over the past year, although the choice of mortgages across the board is around a quarter of what it was five years ago.
