More than a year after WFAA reported on a lawsuit against a popular shampoo sold through an infomercial, the U.S. Food and Drug Administration has now opened an investigation into the product after thousands of complaints.

In March 2015, News 8 reported on a federal lawsuit filed by a Dallas attorney against Hollywood hairstylist Chaz Dean’s WEN Cleansing Conditioner.

According to the initial lawsuit, six women at the time alleged that they lost clumps of their hair after using Dean’s product.

"As I was shampooing my hair with it, I was noticing handfuls of hair," Cindy Peterson, a former customer, told WFAA last year. "Because my hair was so thick, I didn't notice it right away."

Last week, the FDA announced its own investigation after receiving 127 complaints directly from consumers of “hair loss, hair breakage, balding, itching, and rash associated with the use of WEN by Chaz Dean Cleansing Conditioner products.”

The FDA said this is the “largest number of reports ever associated with any cosmetic hair cleansing product, including cleansing conditioners. FDA is also investigating more than 21,000 complaints reported directly to Chaz Dean, Inc. and Guthy | Renker, LLC that FDA learned of during inspections of manufacturing and distribution facilities.”

Peterson hired Dallas attorney Amy Davis to sue Dean and Guthy | Renker — the direct marketing firm that sells WEN products — for negligence, false advertising and breach of warranty, among other things.

The FDA said it isn’t sure what’s causing the reaction some women complain about but the government is calling on the company to “provide any data that might help us to better understand the reports of hair loss.”

"We take great pride in the quality of WEN and take the appropriate steps to ensure every WEN product we sell meets our high standards," said Sarah Elison, Public Relations Manager for Guthy | Renker, in an e-mailed statement to News 8 last year. "We want all our customers to have positive experiences with our products and we encourage any customer with a question to contact us."

Chaz Dean, Inc. responded to News 8's request for a comment Thursday:

"The Wen by Chaz Dean family cares deeply about everyone's hair health. We encourage people who inquire about any hair issues to seek qualified medical assistance because it is a complex topic. WEN® by Chaz Dean is safe, and millions of bottles have been sold over the last 16 years. We have consistently cooperated with the FDA and will continue to do so. We love our brand and our customers. Through this experience, we have learned that there is an immediate need for more education about hair health and common hair concerns in the industry, unrelated to Wen. There is no evidence that WEN products cause hair loss and the ingredients and formulations meet or exceed safety and quality standards set by the cosmetics industry. We stand behind them."