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Can TRESemmé Take You from a Bad Hair Day to a No Hair Day?

Deliberately included in haircare products for its preservative properties, DMDM hydantoin has taken the spotlight for another property — hair loss.

In November 2020, a class-action lawsuit was filed against Unilever for the sale of TRESemmé shampoos that were said to contain hazardous ingredients. Word spread quickly as a viral Facebook post circulated in which a woman claimed that TRESemmé hair products caused her to lose hair by the “brush full” and suffer from scalp irritation. Many other unhappy customers came forward online to share their nightmares using these products. The alleged culprit for the hair loss is DMDM hydantoin, a formaldehyde-releasing preservative, which has since been under scrutiny by the beauty community.

The suit outlines that "the products contain an ingredient or combination of ingredients that causes significant hair loss and/or scalp irritation upon proper application”, in reference to DMDM hydantoin. When in contact with water, the ingredient leaches formaldehyde. It continues, “formaldehyde is a well-known human carcinogen that can cause cancer and other harmful reactions when absorbed into skin”. The lawsuit asserts that Unilever failed to warn its customers of the potential harms of this ingredient. Further, it suggests that with years in the industry and after having lost a previous lawsuit for the same reasons, the company was more than capable of substituting DMDM hydantoin with a safer alternative.

Although TRESemmé intends to refrain from commenting on these allegations just yet, they do claim that their products are “rigorously assessed by leading experts using industry-proven methods”, insisting they are safe. Additionally, they have made no recalls on their shampoos or conditioners following the backlash. Unilever has been given a deadline of February 2021 to respond to these complaints.

So, what exactly is DMDM hydantoin? Let’s take a look at the science.

DMDM hydantoin is added to a variety of cosmetics as a preservative. It operates through the slow release of formaldehyde, which kills microorganisms, preventing the growth of bacteria, fungi, yeast and other pathogens, thus extending the products’ shelf life. Most commonly found in shampoos, conditioners and bodywashes, DMDM hydantoin can also be found in virtually every product in your bathroom. Without some kind of preservative, these personal products would need to be replaced weekly or even more frequently.

It should be noted that even formaldehyde is found in many of your everyday items such as wood products, glues and other adhesives and even in small amounts in various fruits and vegetables. Realistically, the amount of formaldehyde that would be released in any one of your products is comparable to that in an apple. All that to say - although formaldehyde is reported to be carcinogen, it takes long-term exposure to a much more significant source than your shampoo for it to exert any detrimental effects. So, one major consideration is in the amount of DMDM hydantoin found in your products.

The next biggest considerations are allergies and skin sensitivities. A study lead by a dermatologist, Anton de Groot, revealed that formaldehyde-releasing products pose a threat for contact dermatitis (in other words, skin irritation) in individuals with pre-existing formaldehyde allergies. His team used patch tests, a diagnostic tool to determine patients’ skin sensitivities, to assess the reactions. Basically, this means that most people who react to formaldehyde releasers (such as DMDM hydantoin) are allergic to formaldehyde already. These findings were corroborated by a 2018 study which concluded that “patients allergic to formaldehyde often had simultaneous positive patch test reactions to formaldehyde-releasers”. The lawsuit did not contain any evidence that the complainants sought out patch-tests to support their arguments, making their claims solely anecdotal.

This brings us to the suit’s argument that TRESemmé should’ve done a better job at disclosing the associated risks with their product. However, it is not unreasonable to expect those with allergies to take precautions themselves when choosing their own products. After all, someone with a nut allergy will check food labels to ensure safe eating, and peanut butter companies aren’t under fire for omitting “MAY CAUSE DEATH” from their packaging. Admittedly, it is much harder to know whether or not you have a formaldehyde allergy, but the onus is on the complainant to seek a professional opinion before pointing fingers.

While the symptoms suffered by these individuals are very real, and rightfully upsetting, there are many factors at play here. It is suspected the initial risk came from pre-existing allergies or sensitivities and the remaining alarm was exaggerated through fearmongering by the media.

The bottom line is your tried-and-true hair products should not be causing hair loss. It is always important to be aware of the products you are using and to find what is right for you. But for now, the scientific evidence outweighs the anecdotal evidence, and we’ll be waiting for February 2021 to see how TRESemmé responds.

Cat Wang is a biomedical science student at McGill University, specializing in anatomy and cell biology.


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