Kosas positions itself as a clean beauty brand, and most of its products score well on independent safety databases. But “non-toxic” isn’t a regulated term in cosmetics, and a closer look at the brand reveals a more complicated picture that includes low-hazard ratings on most products, some flagged ingredient concerns on specific formulas, and at least one product that tested positive for detectable levels of heavy metals.
What Kosas Leaves Out of Its Formulas
Kosas meets Sephora’s “Clean at Sephora” standard, which requires brands to fully avoid a restricted ingredient list. That list includes parabens, phthalates, formaldehyde and its releasers, chemical sunscreens like oxybenzone, coal tar dyes, cyclic silicones, PFAS (fluorinated compounds like PTFE), sulfates, triclosan, and mineral oil or petrolatum unless highly refined. Sephora can request testing data and safety documentation to verify compliance.
The brand also holds Leaping Bunny certification, meaning its products are not tested on animals. Kosas has been certified since 2018 and currently sells in the US, Canada, Australia, the United Kingdom, and New Zealand, none of which require animal testing for cosmetics.
How Kosas Scores on Safety Databases
The Environmental Working Group’s Skin Deep database lists 208 Kosas products and categorizes the ones displayed as “low hazard.” Products like the Tinted Face Oil, BrowPop pencils, and Cloud Set setting mist all fall into this category. That said, EWG notes that data availability for many Kosas products is only “fair” or “limited,” meaning the ratings are based on incomplete ingredient transparency.
The Revealer Concealer, one of the brand’s best sellers, tells a slightly different story. EWG flags it with a moderate overall concern level, with moderate scores for cancer and developmental or reproductive toxicity and high scores for allergies, immunotoxicity, and use restrictions. These ratings reflect the potential risk profiles of individual ingredients in the formula, not confirmed harm from using the product. Still, it’s worth noting that not every Kosas product earns the same clean bill of health.
Heavy Metals Found in a Kosas Lip Product
Independent testing by Lead Safe Mama, a consumer advocacy site that uses XRF analyzers to screen consumer products, found that the Kosas Sport LipFuel Lip Balm in the shade “Pulse” tested positive for the highest level of lead the site had recorded in any lip balm or lipstick product at the time of testing. The product also tested positive for arsenic.
Trace heavy metals in cosmetics are not unusual. They often come from mineral pigments like iron oxides and titanium dioxide rather than being intentionally added. The FDA allows cosmetics to contain trace amounts of lead (up to 10 parts per million in lipstick, for example), and most products on the market fall well below that limit. But for consumers specifically seeking out “non-toxic” brands, finding elevated lead in a lip product is the kind of result that complicates that label. Kosas does not publicly share third-party heavy metal testing results for its products.
The Mold Problem
Kosas uses paraben-free preservation systems and says all products must pass rigorous preservative efficacy testing under the USP 51 protocol at an independent lab before going to market. Unopened products carry a shelf life of two to three years depending on whether they contain water, and each product includes a PAO (period after opening) symbol on the packaging.
Despite this, the brand has dealt with public reports of mold and spoilage. The Revealer Concealer became the subject of complaints on Reddit, Instagram, and TikTok from consumers who found what appeared to be mold growth in their tubes. This is a known challenge for clean beauty brands broadly: when you remove traditional preservatives like parabens, the alternative preservation systems can be less forgiving of heat, humidity, or products sitting open for months. Kosas has not disclosed which specific preservatives it uses as replacements, making it hard for consumers to evaluate the stability of the formulas themselves.
What “Non-Toxic” Actually Means Here
There is no legal or regulatory definition of “non-toxic” in the cosmetics industry. The FDA does not certify any makeup brand as non-toxic, and no third-party certification uses that exact term. What Kosas offers is a product line formulated without many of the ingredients that clean beauty advocates consider most concerning, verified by meeting Sephora’s internal standards and earning generally low hazard scores from EWG.
That’s a real, meaningful commitment compared to conventional beauty brands. But it’s not the same as saying every Kosas product is free from all safety concerns. Specific products have flagged ingredient profiles, at least one lip product has tested positive for heavy metal contamination, and the brand’s preservative systems have not prevented all reports of microbial growth. If your goal is to reduce your exposure to common cosmetic chemicals like parabens, phthalates, and formaldehyde, Kosas delivers on that. If you’re looking for a guarantee that every product is completely free of any substance that could pose a health concern, no cosmetics brand can honestly make that promise.