Are period underwear safe?
The honest answer, with the caveats that actually matter - PFAS, silver, the regulation gap, and the one place period underwear is genuinely safer than tampons. Every claim on these pages is sourced, and none of it is medical advice.
The short answer
The questions, answered honestly
PFAS in period underwear: the lawsuits, the testing, and what it actually means
What PFAS "forever chemicals" are, the Thinx and Knix class-action settlements, the independent lab testing, and how to read it honestly - what was established and what was not.
Read itAre period underwear FDA-regulated? Why there is no ingredient list
Tampons, pads, and cups are FDA medical devices; period underwear is generally sold as apparel and is not. Neither has to list ingredients - which is the root of the PFAS story. Plus the state laws changing that.
Read itSilver in period underwear: the antimicrobial question
Some period underwear uses silver (sometimes nanosilver) for odor control. What the FDA found about silver and vaginal bacteria, what has and has not been studied, and how to avoid it if you would rather.
Read itPeriod underwear and yeast infections: breathability and vaginal health
Non-breathable synthetics trap heat and moisture, which can raise the risk of yeast infections and irritation for some people. How to lower the risk - cotton gussets, the right absorbency, changing often - without the alarmism.
Read itCan you get toxic shock syndrome (TSS) from period underwear?
Period underwear is an external product, so it does not carry the tampon-associated toxic shock risk. What TSS is, why internal products are the concern, and the honest caveats.
Read itHow we handle safety content
Common questions
- Are period underwear safe?
- For most people, broadly yes, with two caveats worth understanding. Some period underwear has contained PFAS ("forever chemicals") - two major brands, Thinx and Knix, settled lawsuits over it - and some styles use silver as an antimicrobial, whose effect on vaginal bacteria is not fully studied. Neither has to be disclosed on the label. On the other hand, period underwear is external, so it avoids the tampon-associated toxic shock risk. The honest position is: know what to look for, and the deep-dives below give you the sourced detail.
- What is the safest period underwear?
- Look for brands that publish third-party PFAS testing or an OEKO-TEX screening rather than a bare "PFAS-free" claim, prefer a cotton or cotton-topped gusset for breathability, and, if the antimicrobial question bothers you, choose styles that do not add silver. From December 2026 New York bans PFAS in period products (California already restricts intentionally added PFAS), so compliant products are becoming the default.
- What was the Thinx lawsuit about?
- Thinx settled a class action for up to $5 million (reported January 2023) over marketing its underwear as safe and non-toxic while it allegedly contained PFAS. Thinx did not admit wrongdoing - the settlement resolved the marketing claims rather than a court ruling that the product is dangerous. Knix settled a similar suit for $1.4 million and agreed to stop using "PFAS-free" language unsupported by testing.
Shop with this in mind
A cotton-topped pair sidesteps the breathability and (usually) the silver question. Find one that fits and matches your flow - in your browser, nothing stored.