The Food and Drug Administration is using its most severe notice in a recall of more than 6,000 bags of chips in two states because of “undeclared milk.”

The FDA has upgraded a recall of Lay’s Potato Chips to the highest level possible, meaning consuming the chips will cause adverse health consequences. In December, Texas-based food manufacturer Frito Lay recalled a limited number of Lay’s Classic 13oz because the product could contain undeclared milk ingredients.

For many, Lay’s potato chips are a go-to snack. Recently, a serious recall has raised concerns for consumers, especially those with food allergies.