Does Thinx period underwear have PFAS?
Thinx period underwear averages 25 out of 100 on PFAS Authority's PFAS and toxin screen across the 8 Thinx period underwear products graded as of October 2026, below the 48 out of 100 median for the 21 other period underwear brands graded alongside it.
Thinx period underwear averages Poor on our four-band scale. None of them clear our buy threshold. That is above 17% of the period underwear brands we grade.
PFAS Authority is a scoring system, not a laboratory. We do not test products ourselves. Grades are model-based, built from published ingredients, materials, certifications, brand disclosures and third-party lab results where they exist. See the rubric.
What Thinx says and does about PFAS
Thinx settled a class action over PFAS in its period underwear in the Southern District of New York. The plaintiffs’ settlement filing describes a fund of up to $5 million, and under the settlement Thinx agreed to measures that require its suppliers to attest that PFAS are not intentionally added to Thinx period underwear. The settlement is not an admission of wrongdoing. Minnesota’s ban on intentionally added PFAS in menstruation products covers period underwear.
- Legal caseThinx settled a class action in the Southern District of New York over PFAS in its period underwear, with a settlement fund of up to $5 million according to the plaintiffs’ settlement filing. Plaintiffs’ filing via ClassAction.org ↗
- Legal caseUnder that settlement Thinx agreed to measures that require suppliers to attest that PFAS are not intentionally added to its period underwear, and the settlement is not an admission of wrongdoing. Thinx settlement site (archived page) ↗
- Regulatory filingMinnesota’s ban on intentionally added PFAS, in force since 2025, covers menstruation products such as pads, tampons, period underwear and menstrual cups. Minnesota Pollution Control Agency ↗
Sources checked September 14, 2026. A brand statement is the company’s own claim, which we report but have not verified. Our grades are model-based estimates, not lab tests.
Graded and flagged Poor and Bad, we’d swap these
Thinx
Intimates & Sleepwear Thinx for All Women's Period Underwear
- Nylon, spandex, cotton blend with waterproof barrier layer
- PFAS, Thinx's 2021 lawsuit settlement involved PFAS contamination; the company has not disclosed current…
5 hazards checked on this product. See all of them.
Thinx
Cotton Starter Set Period Underwear
- Cotton + proprietary waterproof/absorbent layer coating
- PFAS, Already graded separately at Poor (25/100). Thinx has not disclosed coating chemistry; undisclosed…
3 hazards checked on this product. See all of them.
Thinx
Make The Switch Set Period Underwear
- Cotton/synthetic blend with waterproof coating (composition unspecified)
- PFAS, Undisclosed waterproofing layer is most probable PFAS source. Brand silence and industry norms suggest…
4 hazards checked on this product. See all of them.
Thinx
for All Women's Comfort Brief Leakproof Period Underwear
- nylon/spandex blend with proprietary waterproof absorption layer
- PFAS, Leakproof period underwear commonly relies on fluorinated water-repellent finishes; Icon has not…
Thinx
Super Hiphugger Women Period Underwear
- gusset fabric with moisture-wicking treatment, composition unspecified
- Formaldehyde / VOCs, Moisture-wicking treatments in textiles commonly use formaldehyde-releasing resins or…
4 hazards checked on this product. See all of them.
Thinx
(2 pack) Thinx for All Period Underwear for Women, Super Absorbency, Black, S-xl, Women's, Size: Small
- Cotton/synthetic blend with proprietary waterproof coating
- Waterproof coating composition (undisclosed), The proprietary waterproof layer is not publicly named or…
2 hazards checked on this product. See all of them.
Thinx
For All Period Underwear Size M - New Women | Color: Red/Brown
- Cotton blend with proprietary water-resistant coating (unspecified)
- Proprietary water-resistant coating composition undisclosed, Thinx has not named the coating chemistry…
3 hazards checked on this product. See all of them.
Thinx
Women Intimates & Sleepwear Thinx Hiphugger Period Black
- Cotton blend with unspecified water-repellent coating
- Undisclosed water-repellent coating chemistry, Thinx does not disclose the chemical family of its coating…
5 hazards checked on this product. See all of them.
Better period underwear from other brands
Graded higher than the Thinx average of 25.
Ruby Love
Rubylove First Period Kit +teen Period Underwear
- organic cotton, waterproof backing layer
- A third party reports verifying it as PFAS-free
- Coating degradation and microparticle shedding
2 hazards checked on this product. See all of them.
Lunapads
3-Pack BOOST Brief
- organic cotton blend, water-resistant gusset
- The brand calls it PFAS-free, which we have not verified
- Microplastic shedding from water-resistant barrier
Aisle
Super Hipster
- Organic cotton, wood pulp fiber
- The brand calls it PFAS-free, which we have not verified
- Azo dyes and synthetic dyes
2 hazards checked on this product. See all of them.
The same question, asked of the other period underwear brands
Best average grade first. Thinx averages 25.
See every Thinx product we grade on the Thinx brand page, or the full period underwear ranking.