Dunkin' is being sued for $5 million over claims that the Massachusetts-based coffee chain discriminates against lactose-intolerant customers by charging extra for non-dairy milk.

Filed Dec. 26, the complaint claims that customers seeking non-dairy alternatives like soy, almond or oat milk in their Dunkin' drinks may pay as much as $2.15 extra. Attorneys representing 10 plaintiffs who are either lactose intolerant or who have milk allergies argue that the surcharge for the substitutions is a form of discrimination that violates the Americans with Disabilities Act.

Dunkin', which earned $250 million in revenue between 2018 and 2023, has made substantial profits after it "created a separate, higher-priced menu, aimed at customers who cannot ingest milk," the lawsuit states. It goes on to argue that there exists “no material difference between the price of lactose-containing milks and the price of Non-Dairy Alternatives.”

Dunkin' has until March 4 to respond to the complaint, court records show. The company did not immediately respond Tuesday to USA TODAY's request for comment and no attorneys were yet listed for Dunkin' in court records.

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Complaint seeks $5 million in damages for Dunkin' non-dairy surcharge

The class action lawsuit filed Dec. 26 in U.S. District Court in Northern California is seeking $5 million in damages from Dunkin' on behalf of all the chain's customers who have sought non-dairy substitutions.

Between 2018 and 2023, customers who asked that regular milk be substituted with products like soy, oat, coconut or almond milk were charged anywhere from 50 cents to $2.15 extra, according to the complaint.

At the same time, Dunkin', which reportedly sells roughly 3 million coffee drinks per day, will modify its beverages at no extra cost for those seeking drinks with whole milk or fat-free skim milk instead of the standard 2% milk, attorneys argued in the complaint. The lawsuit also contends that the company similarly doesn't charge extra to make caffeine-free and sugar-free beverages for those who have conditions like hypertension or diabetes.

Attorneys argue that the non-dairy surcharge is not only a federal violation, but also of several state anti-discrimination laws given that lactose intolerance and milk allergies are considered disabilities.

“Dunkin’s policy of charging all customers a surcharge for non-dairy milks disproportionately affects persons with lactose intolerance and milk allergies," Bogdan Enica, one of the attorneys representing the plaintiffs, said in a statement to USA TODAY. "The only choice for this group of people is to pay the surcharge."

What is lactose intolerance, milk allergies?

Those with milk allergies or who are lactose intolerant would suffer adverse health effects such as stomach pain, gastrointestinal inflammation, bowel issues, bloating and vomiting if they consume dairy products, according to the lawsuit.

According to the suit, at least 12% of the population nationwide (and likely more) suffers from lactose intolerance, while more than 15 million people in the U.S. have a milk or dairy allergy.

Lactose intolerance occurs in those whose small intestines do not make enough of an enzyme called lactase to break down and digest the sugar in milk known as lactose, according to the Mayo Clinic. Those with dairy or milk allergies experience an atypical immune system response to such products that can manifest as hives, itching, swelling of the tongue or other symptoms, the Mayo Clinic says.

For these people, the use of non-dairy alternatives in their beverages “is not a choice" and the plaintiffs named in the complaint must “pay careful attention to the drinks they consume,” the lawsuit contends.

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]