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Understanding the Risks of Wearing Period Underwear: What You Need to Know

Dr. Lisa Lawless

Dr. Lisa Lawless, CEO of Holistic Wisdom
Clinical Psychotherapist: Relationship & Sexual Health Expert

Cartoon of underwear with hearts to symbolize period underwearHow Toxicants Were Discovered In Period Panties

In 2020, Mamavation, a watchdog group that tests hormone-disrupting chemicals in women's products, sent 17 pairs of period underwear from 14 brands to Galbraith Labs, accredited by the International Organization for Standardization (ISO).

They requested an ion-selective electrode test, a standard testing method for fluorine. The test revealed that about 65% of the underwear had detectable amounts of fluorine in either the outer or inner layer of the crotch. While not all fluorine-containing compounds are harmful PFAS compounds, they are often associated with adverse health effects.

What Are PFAS?

Perfluoroalkyl and poly-fluoroalkyl substances (PFAS), or "forever chemicals," are found in various consumer products, including non-stick cookware, waterproof clothing, and food packaging. Unfortunately, these they don't break down easily in the environment, so they tend to stick around, hence their nickname.

PFAS have been linked to various health concerns, including developmental delays, hormonal disruptions, and even some types of cancer. And as you all know, our mental and sexual health can also suffer when our physical health is compromised.

The Thinx Lawsuit

Thinx, Inc. was one of the companies who makes period underwear that were found to have PFAS and thus a lawsuit was filed. If you bought period underwear from the company Thinx, you may be entitled to a refund due to a class-action lawsuit settlement announced in November 2022.

Plaintiffs in the lawsuit accused Thinx of using PFAS in their products and not disclosing that to customers. When tested, the Thinx organic brief had 3,264 parts per million (ppm) of fluorine (a strong irritant to skin), and their organic Shorty for teens had 2,053 ppm.

It’s unclear how many other period products contain PFAS or other toxicants because they’re not tested by the Food and Drug Administration (FDA), and manufacturers aren’t required to list all the materials used.

Thinx is now taking numerous measures to ensure that PFAS are not intentionally added to their products at any production stage. This is a positive step toward ensuring customer safety and peace of mind.

In addition, you may be entitled to a refund if you've purchased Thinx period underwear. Customers can receive a refund of up to $7 per purchase of up to three pairs of their period underwear with valid proof of purchase or if purchased directly from them.

PFAS Are In Other Menstrual Products

However, this is not just a problem in period underwear; in a series of lab analyses commissioned between 2020 and 2022 by the consumer watchdog site Mamavation and Environmental Health News, found that 48% of sanitary pads, incontinence pads, as well as panty liners tested contained PFAS. Additionally, 22% of tampons and 65% of period underwear were also found to have them.

One of the analyses showed that out of the 22 products that tested positive for PFAS, 13 were marketed as natural, organic, non-toxic, sustainable, or chemical-free. It's pretty concerning to see that these products were labeled this way, as they contained the harmful substances they eluded they did not.

Some Manufacturers Are Pushing Back

Some manufacturers are pushing back, arguing that, in certain cases, they’re unaware that these substances are in their products because they were not having them 3rd party tested. They also indicate that in most cases, if they are present, they are in quantities so low that they could not cause harm.

That being said, the concentrations in feminine hygiene products tend to be much higher than those permitted in tap water. While they are not ingested they are still a concern because the labia minora and vaginal walls allow for direct absorption into the bloodstream.

In 2023, the EPA and the White House have pledged action that includes the slow phasing out of PFAS. In December 2021, an executive order was signed that included a “buy clean” provision that would phase out the purchase of any products that contain PFAS by 2050.

Why Are PFAS Used?

PFAS are used to manufacture many consumer products due to their ability to resist stains, grease, and water.

While exposure to PFAS has been associated with health risks, the amount of found in some period underwear brands, including Thinx underwear had been confirmed to be minimal before the lawsuit decision in late 2022.

To be safe, it is advisable to keep track of any possible symptoms that may arise. If you have any concerns, it is recommended that you seek advice from a healthcare professional to ensure your well-being.

Some of the most common symptoms of PFAS exposure include:

  • Headaches
  • Nausea and vomiting
  • Dizziness or vertigo
  • Fatigue or weakness
  • Joint pain
  • Elevated cholesterol levels
  • Changes in liver enzymes
  • Decreased kidney function

Choose Safe & Empowering Products

If you see products marketed as non-toxic and say they are free of PFCs, PFOA, PFOS, or PTFE, understand that those are only some of the 9,000 PFAS, which does not mean they are free of them all. Ask manufacturers to verify their testing or certification. These should include their restricted substances list (RSL), which includes what shouldn’t be in certified products. 

You may want to consider learning more about medical grade silicone menstrual cups and discs. For more information see: Menstrual Cups & Discs: The Definitive Guide

If you are concerned about menstrual and other hygiene products, watchdog sites like, Environmental Health News (, and the do testing and reporting on PFAS in many products and may be good resources.

Make A Difference

If you want to get involved, contact your Congress members to require eco labels such as Organic Content Standards (OCS), Global Organic Textile Standard (GOTS), and OEKO-TEX in addition to requiring these tests:

  • Total fluorine test (i.e., Peaslee’s PIGE test)
  • X-ray analyses for heavy metals (i.e., Peaslee’s PIXE test), including on added water- or stain-resistant treatments

In Closing

Prioritizing your health is essential to leading a fulfilling life. That is why we make it our mission to empower individuals to take charge of their physical and emotional wellness, including sexual health.

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