A class action lawsuit has been filed against EOS, claiming its lip balm causes skin to crack, bleed and blister.

According to the suit, filed in California, the plaintiff Rachael Cronin said her lips felt like “sandpaper” several hours after using the product. After she reapplied it to soothe her skin, her lips began to crack, flake and bleed. The next day, she had blisters and rashes on and around her mouth. Her symptoms lasted 10 days.

Cronin’s lawyer Mark Geragos wrote that the affected customers could comprise tens of thousands if not hundreds of thousands of shoppers, and he is seeking damages and asking the company to address the potential health concerns.

EOS, whose products have been used by the likes of Britney Spears and Kim Kardashian, told TIME in an emailed statement, “We firmly believe this lawsuit is without merit. Our products are made with the highest quality ingredients and meet or exceed all safety and quality standards set out by our industry and validated by rigorous testing conducted by an independent lab. The health and well-being of our customers is our top priority and millions of satisfied customers use our products every day, many of whom take the time to share their experiences with us.”