The U.S. Consumer Product Safety Commission said Monday that two children have reportedly coughed out pieces of the whistle that they had sucked into their mouths, including one child who received medical attention.
The safety agency said that parts of the three-inch tall "Hello Kitty Birthday Lollipop" whistle can detach and be inhaled, posing a risk to small children.
McDonald's handed out about 2.3 million of these whistles in the U.S. and 200,000 in Canada from October through November in Happy Meals and Mighty Kids Meals.
Consumers should return the whistle to any McDonald's for a free replacement toy.