In addition, growth in global trade has slowed considerably and a decline in raw material prices is posing problems for economies based on these, while the financial sector in many countries still has weaknesses and financial risks are rising in emerging markets, Lagarde added.
"All of that means global growth will be disappointing and uneven in 2016," Lagarde said, adding that low productivity, aging populations and the effects of the global financial crisis were putting the brakes on growth.
She said the start of normalization of U.S. monetary policy and China's shift towards consumption-led growth were "necessary and healthy" changes but needed to be carried out as efficiently and smoothly as possible.
The U.S. Federal Reserve hiked interest rates for the first time in nearly a decade earlier this month and made clear that was a tentative beginning to a "gradual" tightening cycle.
There are "potential spillover effects," with the prospect of increasing interest rates there already having contributed to higher financing costs for some borrowers, including in emerging and developing markets, Lagarde said.
She added that while countries other than highly developed economies were generally better prepared for higher interest rates than they had been in the past, she was concerned about their ability to absorb shocks.
"Most highly developed economies except the USA and possibly Britain will continue to need loose monetary policy but all countries in this category should comprehensively factor spillover effects into their decision-making," Lagarde said.
She warned that rising U.S. interest rates and a stronger dollar could lead to firms defaulting on their payments and that this could then "infect" banks and states.