SEATTLE — Costco is being sued over a “sugar-free” electrolyte drink mix that plaintiff Mason Maldonado alleged is falsely advertised.
Maldonado, an Illinois resident, claimed Kirkland Signature Hydration Electrolyte Drink Mix does in fact contain sugar in the form of allulose, according to a proposed class-action lawsuit filed in the U.S. District Court for the Western District of Washington and obtained by MyNorthwest.
Costco lawsuit challenges ‘sugar-free’ labeling over allulose ingredient
Allulose is listed as the first ingredient in both flavors, with a note stating it “adds a dietarily insignificant amount of sugar,” according to the complaint. However, the complaint argued allulose counts as sugar under federal labeling rules.
“Allulose is a monosaccharide and, therefore, a sugar under the applicable federal and Illinois labeling standards,” the complaint stated.
The complaint also cited research linking allulose consumption to gastrointestinal effects such as nausea, bloating, diarrhea, and abdominal pain. The complaint used the term “health-washing” to describe the case.
“For as long as consumable goods have been sold, ‘health-washing,’ which is the instigation of a sale of a consumer product by making it appear healthier than it is, has led consumers to buy a product that either does not actually have any health benefits or are, in some cases, harmful,” the complaint stated.
“The instant case is a classic occurrence of health-washing,” it continued. “Here, defendant uses false advertising and deceptive conduct which promises health-related benefits.”
Lawsuit seeks compensation for Costco shoppers and changes to ‘sugar-free’ labeling
Maldonado is asking Costco to compensate shoppers who allegedly overpaid for the drink mix, along with additional damages where permitted by law. Maldonado said he wouldn’t have bought the product, or would have paid less, had he known it contained sugar. He also wants a court order requiring Costco to stop or correct the allegedly misleading “sugar-free” labeling and marketing.
MyNorthwest has reached out to Costco for comment.
Follow Julia Dallas on X. Read her stories here. Submit news tips here.
©2026 Cox Media Group



