The U.S. Food and Drug Administration (FDA) announced that a steamed bun product is being recalled in 27 states after it was found to potentially contain a life-threatening allergen.

Prime Foods Processing, based in Brooklyn, New York, is recalling 477 boxes of its Egg Custard Steamed Buns after discovering they may contain undeclared sesame seeds.

The recall affects two specific products: Steamed Buns with Egg Cream (item no. PD4180) and Steamed Buns with Egg Cream and Coconut (item no. PD4190). The affected batch numbers are #24149 and #24150, with an expiration date of October 2025.

The products were distributed between May 30, 2024 and June 28, 2024 through grocery stores in 27 states: Arizona, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Illinois, Kentucky, Kansas, Louisiana, Massachusetts, Maryland, Maine, Missouri, North Carolina, Nebraska, New Jersey, New York, Ohio, Oklahoma, Oregon, Pennsylvania, Texas, Utah, Virginia and Washington.

The rolls are packed in bright yellow packaging and the batch code is located at the bottom left side wall.

The recall was initiated after an internal investigation found that six boxes of sesame steamed buns had been mistakenly packaged as egg custard steamed buns.

No consumer complaints or illnesses were reported until the announcement on August 9, 2024. However, the company identified a temporary disruption to its packaging process as the cause, which has since been resolved.

The FDA and Prime Foods urge consumers who purchased these products to return them to the store where they were purchased for a full refund.

Consumers are also advised not to consume the products, even if they have already been opened.

Symptoms of an allergic reaction include rash, hives, itching, vomiting and/or diarrhea, abdominal cramps, swelling of the throat and vocal cords, and coughing or wheezing.

Allergic reactions can cause serious harm and even be fatal if they trigger anaphylaxis, in which the body’s immune system overreacts to the presence of the allergen.

Sesame is one of the FDA’s nine major allergens. The others are wheat, milk, tree nuts, peanuts, soy, eggs, crustaceans (shellfish), and fish. Food manufacturers are required by law to clearly label the nine most common allergens on all products.

According to the FDA, which sets food labeling regulations in the United States, when a food label contains a “Contains” statement, it must include the names of the food sources of all major food allergens used as ingredients.

Newsweek contacted Prime Foods outside of business hours via online form to provide a comment.