PFAS in Period Underwear: What to Know

Period safety guide

Quick answer

To find period underwear without PFAS, ask the brand for recent lab results from an outside lab. PFAS are man-made chemicals that help things resist water and stains. Tests have found them in some period underwear. Poison control experts say there's no proof yet that this harms health, but it's fair to ask.

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A fabric swatch tested in a lab, the kind of PFAS result you can ask period underwear brands for
  • PFAS are man-made chemicals that help things resist water and stains.
  • Tests have found PFAS in some period underwear.
  • Experts say there's no proof yet that this harms health.
  • Ask any brand for recent third-party lab results.
  • Questions about Kischt? Email hello@kischt.com.
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What are PFAS?

PFAS are a big group of man-made chemicals. They have been used since the 1940s. They help things like rain jackets and carpets resist water and stains.

People call them forever chemicals, because many break down very slowly. Some PFAS may be linked to health problems. Scientists are still learning more.

Why ask about PFAS in period underwear?

Period underwear is made to stop leaks. PFAS can help fabric push away water. So people ask if leak-resistant layers have them.

Tests have found PFAS in some period underwear. A 2025 Notre Dame study found most samples had low levels. But some looked like they were treated on purpose. Poison control experts say there's no proof yet that PFAS in period underwear harms health.

Should you stop wearing period underwear?

There's no need to panic. NASPAG, a group of gynecology experts, says people should not be alarmed if they have used period underwear. It notes that food and water are where we get the most PFAS. If you want to know more, ask the brand for its lab results.

How do you know if period underwear is PFAS-free?

  1. Ask for lab results

    Ask the brand for recent PFAS test results from a third-party lab. That means an outside lab, not the brand.

    Woman comparing period underwear brands with a checklist of PFAS questions to ask

  2. Check what was tested

    Ask if the test covered the whole pair, inner layers too. Ask for the test date.

  3. Ask if PFAS are added on purpose

    A Notre Dame PFAS researcher says to ask brands this question.

  4. Look past the label

    Words like clean or non-toxic can mean different things. Lab results tell you more.

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Common questions

Is there PFAS-free period underwear?

Some brands say their underwear has no added PFAS. The best proof is recent results from an outside lab. Ask the brand to share them.

What are forever chemicals?

It's a nickname for PFAS. Many PFAS break down very slowly, so they can build up in people and nature over time.

Are PFAS in period underwear harmful?

Poison control experts say there's no proof yet that PFAS in period underwear harms health. Some PFAS may be linked to health problems, and research goes on.

Do PFAS wash out of period underwear?

No one knows yet. Poison control experts say it's unclear whether washing removes PFAS.

How can I check a brand for PFAS?

Ask for recent third-party lab results. Check that every layer was tested, and ask if PFAS are added on purpose.

More guides

See all guides: Period Underwear Guide: Every Question Answered

Sources

  1. EPA: Our Current Understanding of the Human Health and Environmental Risks of PFAS
  2. CDC / ATSDR: PFAS Information
  3. Harvard T.H. Chan School of Public Health: Questions Raised About PFAS in Period Products (January 2023)
  4. New Jersey Department of Health: Period Underwear
  5. University of Notre Dame: PFAS in Reusable Feminine Hygiene Products (July 2025)
  6. Poison Control (National Capital Poison Center): Is Period Underwear Safe to Use?
  7. NASPAG: Response to Headlines Concerning PFAS in Period Underwear

Updated by the Kischt team.

This page is general information, not medical advice. See a doctor if you are worried about your health.

Returns: you have 30 days after you get your order to request a refund. Details are in the return policy.