Consumers borrowed a further £1.6bn in January, the second-highest level for more than a decade, according to figures from the Bank of England.
Compared to the same month a year ago, unsecured consumer credit rose by 9.1%.
Borrowing was slightly higher in November 2015, but otherwise the figure was the largest since June 2005.
Experts said one reason was shoppers taking advantage of bargains in January's clearance sales.
"January's spike back up in unsecured consumer credit may fuel concern that consumers are borrowing more and saving less to finance their spending," said Howard Archer, chief UK economist with IHS Global Insight.
The Bank also reported that the number of home-owners taking out mortgages rose to a two-year high in January.
A total of 74,581 mortgages were approved in the month, the highest level since January 2014.
The Council of Mortgage Lenders (CML) and the Royal Institution of Chartered Surveyors (Rics) have already said that buy-to-let landlords have been rushing to buy property, ahead of stamp duty changes.
In April, landlords and second homeowners will face a 3% surcharge on stamp duty when buying a property.
However some experts said that demand for homes was likely to slow in the coming months.
"The beginning of 2016 has been far busier than usual in the mortgage market, but between now and June activity is likely to slow as the possibility of Brexit makes people more cautious," said Martin Stewart, managing director of mortgage broker at London Money.