Are period underwear safe?
The answer, with the caveats that 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 with sources
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 what was established and what was not.
Read itAre period underwear FDA-regulated? Why there is no ingredient list
Yes, as a Class I menstrual pad: manufacturing and labeling rules, but no review before sale and no ingredient list. What that gap means for you.
Read itSilver in period underwear: the antimicrobial question
Some period underwear uses silver, sometimes nanosilver, for odor control. What a 2018 lab study found, what has not been studied, and how to avoid it.
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 for some people. How to lower it, without the alarmism.
Read itCan you get toxic shock syndrome (TSS) from period underwear?
Period underwear is external, so it does not carry the tampon-associated toxic shock risk. What TSS is, why internal products are the concern, and caveats.
Read itHow we handle safety content
Common questions
- Are period underwear safe?
- For most people, broadly yes, with two caveats worth understanding. Independent testing has found PFAS ("forever chemicals") in some period underwear, and two brands, Thinx and Knix, settled class actions in 2023 over PFAS marketing claims without admitting wrongdoing; 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. Know what to look for; 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 in 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 and agreed to make "PFAS-free" claims only with testing behind them. The amounts, dates and what each settlement did and did not establish are in the PFAS guide below.
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.