In a new assessment of global economic conditions, the IMF said many countries worldwide are battling disinflation - low and slowing inflation - due to weak global economic growth.
If central banks around the world cannot halt this stall, and if companies and people increasingly believe they can't halt it, their economies risk sinking into a deflationary spiral - where prices generally start to fall and companies and consumers hold back spending and investment, stalling the economy.
The report said deflationary pressures in many countries are coming from abroad, in the form of sinking prices of both commodities and manufactured goods.
"The breadth of the decline in inflation across countries and the fact that it is stronger in the tradable goods sectors underscore the global nature of disinflationary forces," the IMF said.
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Weak inflation challenges central banks' ability to use monetary policy to stimulate demand, the IMF notes, because interest rates are likely to already be very low, giving them little room to cut further.
"Eventually, 'persistent' disinflation can lead to costly deflationary cycles - as we have seen in Japan - where weak demand and deflation reinforce each other, and end up increasing debt burdens and hindering economic activity and job creation."
Part of the problem is about perceptions - if people expect that inflation is going to slow whatever the central banks do, it further undermines the effectiveness of monetary policy.
"After a long period of stability, certain measures of medium-term inflation expectations have indeed fallen in some advanced economies.