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Allegations of mold in Kosas concealer have customers questioning the 'clean' beauty movement

The makeup brand came under fire after a months-old Reddit post resurfaced on TikTok.
Kosas' Revealer Concealer
Kosas' Revealer Concealer.Kosas Cosmetics

Kosas, a makeup brand focused on “clean” beauty, is under fire after a months-old Reddit post about a consumer finding mold in its concealer resurfaced on TikTok — raising questions among consumers over the clean beauty movement sweeping the makeup industry.

Kosas describes its products as “skin-improving” and says it uses “minimum ingredients for maximum impact.” Many clean beauty brands, including Kosas, say their products are free of parabens, phtalates, sulfates, talc, aluminum and a bevy of other chemicals typically used in cosmetic products.

The brand’s wildly popular Revealer Concealer has been touted as an essential product for anyone trying to achieve the “clean girl aesthetic,” which is an aspirational beauty trend that espouses “no-makeup” makeup and effortless, slicked-back hair.

But in recent weeks, some TikTok users have complained of their concealer developing rancid odors and causing skin irritations. As their videos went viral, so did a rumor claiming that the Kosas product developed mold, fueling further backlash against the brand and the clean beauty movement as a whole. As the videos continue to circulate, some on TikTok and Reddit have questioned the safety of clean beauty products as a whole.

The claim surrounding the concealer appears to stem from an eight-month-old Reddit post in r/Makeup, in which the original poster alleged they found “black spots” in their concealer more than a year after opening it, and that the product smelled like “blue cheese.” They also claimed the product burned their skin when they tried it. 

When asked about the online criticism of the product, a representative for Kosas directed NBC News to the brand’s FAQ page, which states that Kosas uses “safe, effective preservatives and antimicrobial stabilizers which prevent against mold, yeast and pathogens.” 

The brand has also been directly responding to some of the criticism in TikTok comments. When one user posted a video of her concealer and questioned if the discoloration in the product was mold, the Kosas brand account clarified that it was just the concealer separating and “clinging to the sides” of its packaging.

Jane Tsui, a cosmetic chemist who oversees product formulations for beauty brands, said “every brand has hiccups" and that Kosas is likely receiving so much backlash “because they have been such a fast-growing popular brand."

Cosmetic packaging should include a jar symbol, known as the Point After Opening (PAO) symbol, that informs consumers of the product’s useful lifetime after they open it. The PAO on the Revealer concealer says 6 months, which means that the product may no longer be stable after that time period.

Tsui said that expecting consumers to replace their makeup so often is "unrealistic," but urged consumers to monitor their products closely after its PAO date — especially if they start to smell or cause new skin irritations.

“Eyeliner or mascara, or things that come in more contact with your eye,” Tsui said, “I would definitely suggest tossing those sooner rather than later.”

But some TikTok users say that their concealer developed odors and caused new skin irritations before their products’ PAO date. One Reddit user said that the concealer they purchased “lasted half its shelf life before it started to give off an awful stench.” Several cosmetic chemists on TikTok have raised concerns over the concealer’s stability, since it uses alternative preservative ingredients.

Cosmetic chemist Javon Ford told TikTok viewers that potassium sorbate and sodium benzoate, which are in Kosas’ Revealer, are “better at killing mold and fungus than they are at killing bacteria." He also noted that the formula doesn't contain a chelator, a compound that inhibits bacterial growth.

Cosmetic chemists test products in a variety of different conditions, and typically aim for a product to remain stable for three months at 40 degrees Celcius. In a recent video, Tsui suggested that the product may have passed tests at the time of production, but questioned if it would have passed testing at three and six months.

Instead of going the clean route, personally, I would love to see more education around specific ingredients

-Jane Tsui, a cosmetic chemist

A product like concealer, which uses a wand to make direct contact with skin before it’s stored in its tube, has “more room for contamination,” Tsui said. Products that are “natural” and products that use synthetic ingredients may pass testing when they're made, but can change when new bacteria is introduced.

“Kosas wouldn’t be the only or the first brand to run into that issue,” she said. “It’s something that a lot of brands on the market you may know have run into, and sometimes you got to do a recall and look at it.”

The burgeoning clean beauty movement markets products free of “synthetic” chemicals, in favor of “natural” ingredients like algae and caffeine. Some brands label their products as “clean” because they’re vegan and don’t test on animals, while others say they aim to lessen their environment impact by using alternative ingredients. While some research has linked certain chemicals to health effects, “natural” ingredients are not inherently safer or nontoxic, Tsui said.

“A lot of times materials that are synthetically made can function just as well or even better than something that’s ‘natural,’ and there’s so much perception that synthetically made ingredients are more harmful because they’re not natural, but that’s simply not the case,” Tsui said. “A lot of research has been done on it to make sure that they’re safe.”

Parabens, a commonly used preservative, have been linked to increased estrogen levels and one study detected the chemical in breast cancer tissue. Though research into the chemical’s long-term effect on health is still inconclusive, the beauty industry has largely shunned the use of parabens. But substitute preservatives can still be harmful or irritating, or not be as effective. In 2019, Glossy reported an increase in microbial contamination alerts in beauty products, which the Food and Drug Administration publishes on its site.

Online, some makeup enthusiasts appear tired of the sweeping claims that some clean beauty brands make — on popular makeup subreddits, users have debated whether the movement is helpful for those with sensitive skin, or if it's just a "marketing gimmick."

In a recent Reddit thread in r/MakeupAddiction, users criticized the brand Saie for an Instagram post about the ingredients it does not use in its products, like mineral oil and petrolatum. Some users pointed out that petrolatum, which is the main ingredient in Vaseline and Aquaphor, is a staple in their skincare routines. 

“A lot of ‘clean’ beauty products also smell TERRIBLE,” a Reddit user commented on another post. "Yes I’m looking at you Ilia, and your hamster-cage-scented tint."

Representatives for Saie, Ilia, Vaseline and Aquaphor did not immediately respond to requests for comment.

Tsui said that she and many of her colleagues aren’t against the clean beauty movement, but they are “confused by it,” since brands themselves don’t “have a good reason” for avoiding traditional cosmetic ingredients. 

“Instead of going the clean route, personally, I would love to see more education around specific ingredients,” Tsui said. “Rather than saying ‘fragrance-free, sulfate-free, paraben-free.’ A ‘free-from’ ingredients list, I think, is more harmful than just explaining why something is in there.”