Celebrity stylist Chaz Dean, based in Hollywood, and his Wen Hair Care products, along with Santa Monica direct marketing firm Guthy-Renker, are the subjects of a class action lawsuit in which people in 40 states nationwide say the products made them lose their hair, CNBC reports.

Among the allegations are that the use of a particular conditioner resulted in hair loss as well as rashes, hair breakage and scalp irritation.

Guthy-Renker has heavily marketed the products, including on late-night infomercials. It is contesting the claims, saying, “There is no scientific evidence to support any claim that our hair care products caused anyone to lose their hair.”