Federal regulators have upgraded a product recall of Lay's Classic Potato Chips to the highest risk level for a batch that may contain undeclared milk ingredients.

Last month, Frito-Lay issued a recall warning that more than 6,300 of its 13-ounce bags may contain undeclared milk posing a risk of a serious or life-threatening allergic reaction. On Monday, the U.S. Food and Drug Administration classified the recall as "Class I," the most severe risk level.

According to the FDA, "Class I" level recalls are used when there is "reasonable probability that the use of, or exposure to, a violative product will cause serious adverse health consequences or death."

The alert states that the batch of chips were distributed in Washington and Oregon and the chips were available for purchase as soon as Nov. 3, 2024.

Frito-Lay representatives did not immediately respond to USA TODAY's request for comment.

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When was the recall issued?

Frito-Lay issued the limited recall on Dec. 16 for 6,344 of its 13-ounce Lay’s Classic Potato Chips bags.

The FDA alert stated the the bag of chips “may contain undeclared milk, after being alerted through a consumer contact.”

“Those with an allergy or severe sensitivity to milk run the risk of a serious or life-threatening allergic reaction if they consume the recalled product,” the alert said.

What potato chips are being recalled?

Which states were the Lay’s chips distributed to?

According to the recall, the bags of chips were distributed to “certain retail stores and e-commerce distributors.”

The recalled chips are only in the following states:

• Oregon
• Washington

What should you do if you have the recalled chips?

People who may have an allergy or sensitivity to milk should not consume the product, the alert said.

Frito-Lay is encouraging people who may have the recalled chips to discard it immediately.

If you have any questions or concerns about this recall, you may contact Frito-Lay Consumer Relations at 1-800-352-4477 on Monday through Friday between 9 a.m. and 4:30 p.m. CT.

What is a milk allergy?

A milk allergy typically occurs when a person consumes a product that contains milk, according to the Mayo Clinic, and the treatment for people who have a milk allergy is to avoid products that may contain milk.

Milk allergies and milk intolerance are a little different from each other, according to the Mayo Clinic.

“A true milk allergy differs from milk protein intolerance and lactose intolerance," according to the Mayo Clinic. “Unlike milk allergy, intolerance doesn't involve the immune system. Milk intolerance requires different treatment from true milk allergy.”

Symptoms of a milk allergy include:

• Hives
• Wheezing
• Itching or tingling feeling around the lips or mouth
• Swelling of the lips, tongue, or throat
• Coughing or shortness of breath
• Vomiting

A milk allergy can cause anaphylaxis, a severe, life-threatening reaction to an allergen that can obstruct a person’s breathing, the Mayo Clinic said.