U by Kotex Ultra Thin Pads
Waterproof coating unspecified; PFAS risk unclear without disclosure.
U by Kotex does not publicly disclose PFAS status or waterproof treatment chemicals. Period pad backsheets typically use water-resistant coatings that may contain PFAS, though specifics remain undisclosed.
The safe swap
Tampax
TAMPAX PEARL ULTRA ABSORBENCY*18 COUNT
70/100 safety
Same rubric that flunked this product. The swap earned Good.
Still want this one anyway? Check the price on Amazon. We’d swap it.
Material
cellulose/rayon with proprietary absorbent core and waterproof barrier
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
What’s concerning
Waterproof / stain-resistant treatment
water-repellent coating treatments have historically used PFAS.
Category baseline
period care is a category where PFAS exposure is more common.
No PFAS disclosure
No public statement about PFAS in this product.
PFAS
Kotex has not disclosed the chemical identity of the waterproof barrier layer. Many conventional pad manufacturers use fluorinated polymers (PFAS-containing) for this function; without testing or disclosure, risk cannot be ruled out.
Source: ATSDR ↗Bacterial or mold growth from moisture retention
If a pad is worn longer than recommended or stored in a warm, humid environment after opening, natural conditions favor bacterial growth; this is inherent to any absorbent pad design and not specific to Kotex formulation.
What’s reassuring
Bleach residue (chlorine)
Kotex has disclosed chlorine bleach use in some pad lines for cellulose whitening, though U by Kotex Ultra Thin does not list this. No residual chlorine is expected in the final product, but the brand's vague sourcing makes full certainty impossible.
Fragrance or fragrance allergens
U by Kotex Ultra Thin is advertised as fragrance-free on packaging. No known fragrance allergens documented for this line, unlike scented Kotex variants.
Azo dyes in printed graphics
The external printed designs on the pad wrapper are not intended for skin contact. No hazard has been reported; standard practice ensures printing inks do not migrate to absorbent layers.
The full breakdown
What it's made of and why it matters
U by Kotex Ultra Thin uses a cellulose and rayon absorbent core (wood-derived fibers) with a proprietary waterproof barrier layer and adhesive backing. The rayon is typically viscose processed from wood pulp, which is safe in end-use form but the barrier coating, likely plastic-based to prevent leakage, is where PFAS chemicals are often added to impart water repellency. The absorbent materials themselves (cellulose, rayon, superabsorbent polymers like sodium polyacrylate) have no established safety concern for vaginal contact in this application.
The brand's record and disclosure
Kotex (owned by Kimberly-Clark) has not publicly disclosed whether their waterproof barrier contains PFAS or fluorinated compounds, nor have they published third-party testing or certification (e.g., BlueSign, GOTS, or OEKO-TEX) for period products. The brand has faced scrutiny for undisclosed fragrance and chlorine bleach use in some pad lines, though U by Kotex Ultra Thin does not list added fragrance. No recall history exists for this specific product. Their silence on PFAS and barrier coating chemistry is notable given increasing consumer concern.
How it compares in its category
Major competitors like Seventh Generation Free & Clear, Organyc, and Cora explicitly state PFAS-free formulations or publish material safety data; Kotex has not. U by Kotex Ultra Thin is priced as a mainstream, non-premium option (lower cost than organic or eco-certified brands), which correlates with less rigorous disclosure but also no proven hazard above standard period pads. Among conventional pads, it sits in the middle range for transparency; some competitors (like Always) are equally opaque, while others lead on disclosure.
If you buy it
Use as directed; there is no evidence of hazard from normal vaginal contact with this pad. Do not incinerate pads at home or in uncontrolled settings, as burning waterproof coatings may release fluorinated gases if PFAS is present (though municipal waste incineration is designed to handle this). Replace pads every 4-8 hours depending on flow; prolonged wear increases bacterial overgrowth risk unrelated to the pad material. If you have vulvar sensitivity, patch-test first or switch to a fragrance-free, PFAS-transparent brand (e.g., Seventh Generation Free) to isolate any reaction.
What we don’t know
- Basis
- Model estimate, 45% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- Kotex has made none
Formulations change between production runs, so check the current label. How we grade.
Safer alternatives in Period Pads
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rayon/viscose, cotton, and gelling polymers
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Limited concern
Irritation or allergic sensitization from adhesive or synthetic fibers
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Lower concern. Typical period pad materials lack PFAS triggers.
⚠Risky category by default
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/ Maternity Pad Maxi Super Absorbency NON241279
cellulose, polyethylene, absorbent core (typical period pad materials)
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High concern
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⚠Risky category by default
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OC BON Ultra Thin Wings Sanitary Pads Medium 4P
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Adhesive contact sensitivity
Limited concern
Bleaching residues in cellulose
Limited concern
Lower concern. No PFAS-prone materials publicly identified.
⚠Risky category by default
More period pads grades
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.