TRESemmé Hair Loss Lawsuit Alleges DMDM Preservative Caused Severe Hair Shedding

Research naming DMDM as a formaldehyde-producing chemical has fueled lawsuits alleging shampoos and conditioners containing the preservative may cause hair loss and other injuries.

Six women from Oklahoma, Maine, Alabama, West Virginia, Texas and Massachusetts have filed a lawsuit alleging they suffered hair loss, thinning hair, allergic reactions and other scalp side effects after using TRESemmé shampoo or conditioners.

The complaint (PDF) was brought by Tarrah Kinney, Johanna Wheeler, Carliss Eaton, Jennifer Kiggans, Jeannie Walker and Kristina Sinclair in the U.S. District Court of New Jersey on July 14. It names Conopco Inc., doing business as Unilever Home & Personal Care USA, as the defendant.

The plaintiffs allege Unilever knowingly used DMDM hydantoin, a formaldehyde preservative, in their TRESemmé hair products. They argue the preservative has been known to cause scalp side effects for users, and the company has known about these kinds of problems for more than a decade.

DMDM Hydantoin Health Risks

DMDM hydantoin functions as a preservative that helps increase the shelf life of personal care products and reduces the growth of microorganisms. However, research has long shown DMDM may also carry harmful side effects including hair loss, allergic reactions, immune system concerns and other risks.

Researchers have identified DMDM as a formaldehyde-releasing ingredient and known human carcinogen, with evidence suggesting repeated exposure may increase the risk of adverse reactions. As a result, numerous lawsuits have been brought over the use of DMDM in hair products.

A lawsuit filed against Unilever in 2023 claimed DMDM hydantoin in TRESemmé products caused users to suffer hair loss and scalp injuries. A separate class action lawsuit filed against the company in 2012 over its line of Suave shampoo and conditioners containing DMDM claimed users of those products also suffered hair loss and shedding, as well as damage to the scalp. That lawsuit resulted in a more than $10.2 million settlement.

TRESemmé DMDM Damage Allegations

The lawsuit alleges the six women suffered significant hair loss after using TRESemmé shampoos and conditioners containing DMDM hydantoin.

According to the complaint, Unilever marketed the products as capable of smoothing hair, adding softness and shine, reducing frizz and tangles, and “deeply nourishing” and “repairing” damaged hair.

However, plaintiffs contend Unilever has known since at least 2012 that products containing DMDM hydantoin were associated with hair loss and scalp injuries. The filing alleges the company received hundreds of consumer reports involving hair damage and compensated more than 400 users who reported injuries after using Suave products containing the ingredient.

Despite those reports and prior lawsuits, the plaintiffs allege Unilever continued selling TRESemmé products containing DMDM hydantoin even as it reformulated some of its other brands and competitors removed the ingredient from similar products.

The complaint further alleges Unilever never warned consumers on its website or product labels that TRESemmé products could increase the risk of hair loss or scalp injuries, despite being one of the world’s largest shampoo manufacturers.

“Defendant has known of the dangers of DMDM since at least late 2012, and has concealed from, or failed to, notify each Plaintiff and the public of the full and complete nature of the dangers, including skin irritation and hair loss, even after receiving numerous reports of injuries from consumers and being sued by consumers for skin injuries and hair loss.”

— Tarrah Kinney et al. v Conopco Inc.

The lawsuit raises allegations of strict product liability for manufacturing defect and design defect, failure to provide adequate warning and negligence. It is seeking punitive damages, compensation for physical injury, pain and suffering, and medical treatment.

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