U by Kotex Ultra Thin Pads, Heavy Absorbency
Skip until brand discloses waterproof layer composition.
U by Kotex does not publicly disclose PFAS status or waterproof coating materials. Heavy-absorbency pads typically use water-repellent treatments, which commonly contain PFAS, but this brand provides no transparency.
The better-graded swap
Aunt Flow
Aunt Flow Pads
100/100 safety
Same rubric that flunked this product. The swap earned Excellent.
Still want this one anyway? Check the price on Amazon. We’d swap it.
Material
rayon/cellulose core, synthetic back/wings, waterproof layers (unspecified)
Lab data
No public lab test
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What U by Kotex Ultra Thin Heavy Absorbency is made of, ingredients and materials
U by Kotex Ultra Thin uses a rayon or cellulose-based absorbent core, which is derived from wood pulp and poses no established chemical hazard in period care products. The back and wings are synthetic polymer (likely polypropylene or polyethylene), which does not leach under normal use conditions. The waterproof layer composition is not disclosed by the brand; in the industry, these are typically made with Teflon-type coating, polyurethane, or fluorinated compounds to create a moisture barrier. This undisclosed waterproof treatment is the critical unknown.
What’s concerning
Waterproof / stain-resistant treatment
Water-repellent coating treatments have historically used PFAS.
Category baseline
The starting point for this type of product, before anything specific to this product is counted.
No PFAS disclosure
No public statement from the brand about PFAS in this product.
PFAS
Waterproof backing layer material is not named on packaging or brand website. Industry standard use of PFAS in period product waterproofing is well documented; Kotex's silence suggests no PFAS-free claim, implying probable presence.
Source, ATSDR ↗Fragrance or adhesive allergens
U by Kotex Ultra Thin is lightly scented in some variants. Fragrance compounds and adhesives used to attach wings can trigger contact dermatitis in sensitive individuals. Brand does not list fragrance ingredients.
What’s reassuring
Rayon/cellulose core purity and bleaching byproducts
Rayon is a regenerated cellulose fiber; bleaching during manufacture can leave trace dioxins or chlorine residues. No recalls or testing data specific to U by Kotex pads indicate a problem, but full chemical disclosure of processing would be reassuring.
Synthetic polymer (back/wings) degradation or microplastic shedding
Polypropylene and polyethylene backings do not break down or shed microparticles under normal period pad use (body contact, moisture, no heat). This hazard is not reported for this product category.
Formaldehyde / VOCs
Period pad cores and synthetic layers are not typically finished with formaldehyde-releasing compounds, as these are used in textiles and apparel. No evidence of this hazard in period care products exists.
Source, ATSDR ↗How is this PFAS grade calculated?
The brand's record and disclosure
Kotex (Kimberly-Clark) does not publicly disclose the composition of waterproof or moisture-barrier layers in period care products on packaging or websites reviewed. The brand has not issued statements about PFAS avoidance or use. No recalls or formal safety controversies specific to U by Kotex Ultra Thin pads are on record in FDA or consumer databases. This silence on waterproofing chemistry is a significant transparency gap in a category where PFAS use is common.
How it compares in its category
Period pads universally require waterproof backing; most major brands (Kotex, Tampax, Always, Stayfree) do not disclose whether these layers contain PFAS. Brands like Seventh Generation, Cora, and some store organic lines have begun testing PFAS-free formulations, though independent verification is limited. U by Kotex sits in the mainstream, mid-cost segment with no claimed PFAS avoidance or certification. If PFAS exposure during period care is a priority for you, alternative brands with explicit waterproof-layer disclosure are preferable.
If you buy it
No special care is needed during use; pads are single-use disposal products not subject to heat or chemical exposure risk. Standard disposal in trash is appropriate. If skin irritation, allergic rash, or odor develops after switching brands, discontinue and try an alternative. Keep pads in a dry location; moisture will not compromise the product. If you have a latex or synthetic polymer sensitivity, patch-test a small area of the wing or back layer against skin first.
What is not known about PFAS in this product?
- Basis
- Model estimate, 42% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- U by Kotex has made a specific claim
Formulations change between production runs, so check the current label. How we grade.
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- Fragrance allergens (if scented variant)
2 hazards checked on this product, all on its full breakdown.
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- The brand calls it PFAS-free, which we have not verified
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- Cardboard applicator structural integrity over time
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25Cora Free To Flow Period UnderwearCompare vs Natracare →All period care →How we score, every product runs through the same public 0-100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.