Two products, two different rulebooks
Tampons, pads, and menstrual cups are regulated by the US FDA as Class II medical devices. Period underwear generally is not - it is sold as apparel, a textile, so it does not go through the device pathway at all. And here is the part that surprises people: even the FDA-regulated menstrual devices are not required to print an ingredient list. Being a regulated device controls how a product is cleared for sale; it does not force disclosure of what it is made of.
Why the gap matters
No ingredient-disclosure requirement means a shopper cannot look at the label and see whether PFAS or silver were used. That vacuum is exactly what independent lab testing and the class-action lawsuits stepped into - they became the disclosure mechanism the label was not providing. It is also why a brand that voluntarily publishes third-party testing is doing something meaningful: it is opting into transparency the law does not require of it.
What is changing: state laws
States are closing the gap. New York passed the first menstrual-product ingredient-disclosure law in 2021, requiring intentionally added ingredients to be listed. New York has since gone further with a law banning PFAS and other toxic chemicals in period products, taking effect in December 2026, joining a group of states (around eight) that ban PFAS in period products. California's T.A.M.P.O.N. Act bans intentionally added PFAS in menstrual products, including period underwear. So the disclosure-and-safety floor is rising, state by state, even though the federal rules have not changed.
Sources
The regulatory facts above trace to:
- FDA regulates tampons/pads/cups as Class II medical devices, with no mandatory ingredient disclosure: FDA guidance as reported by CBS News and Poison Control.
- New York 2021 ingredient-disclosure law, and New York PFAS-in-period-products ban effective December 2026: NRDC.
- California T.A.M.P.O.N. Act (bans intentionally added PFAS in menstrual products including period underwear): Bloomberg Law.
Quick answers
- Are period underwear FDA approved?
- No - and neither "approved" nor "cleared" really applies. Period underwear is sold as apparel, so it does not go through the FDA device pathway that tampons, pads, and cups do. That is not a safety verdict either way; it just means there is no FDA review of it as a menstrual device.
- Do period underwear have to list their ingredients?
- Federally, no. There is no US requirement to print an ingredient list on menstrual products, device or apparel. Some states are changing that: New York has required intentionally added ingredients to be disclosed since 2021, and more states are following.
- Which states ban PFAS in period products?
- Around eight states have passed PFAS bans covering period products. New York's takes effect in December 2026, and California's T.A.M.P.O.N. Act bans intentionally added PFAS in menstrual products including period underwear. Check your state, since the effective dates differ.
Related guides
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.
Silver 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.
Can 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.
The rest of the safety picture
The regulation gap is why PFAS and silver could show up unlabeled. The safety hub covers both, plus TSS and vaginal health, each sourced.