But Lagarde - in a speech to a meeting of central bankers in the US city of Jackson Hole, Wyoming - said that despite the narrowing options, there is still a path to recovery, and "resolute action will help to dispel doubts."
"In sum, risks to the global economy are rising, but there remains a path to recovery. The policy options are narrower than before but there is a way through," the managing director of the International Monetary Fund said on Saturday.
"I am confident that with the right actions, strong, sustainable, and balanced growth can and will be restored," she said.
She spoke a day after Federal Reserve chairman Ben Bernanke said the bank could do little at this time to enhance economic growth and called on US political leaders to do more to boost jobs and the housing market.
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Lagarde also called for "a new approach based on bold political action, with a comprehensive plan across all policy levers, implemented in a coordinated global way".
"Clearly, the scope for policy action is much narrower today than in 2008. There are no easy solutions, but that does not mean there are no solutions.
"Put simply, while fiscal consolidation remains an imperative, macroeconomic policies must support growth," she said.
