The Best Period Underwear Without PFAS (2024 Update)

We contacted 14+ brands of period underwear to find the best non-toxic options.

We asked them about the materials they use, their certifications, if they apply antimicrobial treatments, and whether they’ve tested for PFAS.

Thinx was the trailblazer in period underwear, making its debut in 2014. It quickly became the go-to brand for menstrual panties in households everywhere.

Fast forward to March 2020, when Jessian Choy, a journalist for Sierra Magazine, shared some startling news. Independent lab tests on period panties had uncovered something pretty concerning.

The tests, which were carried out at the reputable Notre Dame University, revealed that Thinx panties contained per- and poly-fluoroalkyl substances (PFAS). These toxic chemicals have been linked to some pretty serious health problems, like cancer, reproductive issues, and endocrine disruption. The researchers found fluorine in the samples, a telltale sign of PFAS.

PFAS are also known as “forever chemicals” because their unique chemistry means they don’t break down under normal environmental conditions, which also results in the bioaccumulation of PFAS in the body (concentration increases inside the body over time). PFAS have been used in industry and consumer products since the 1940s, and the major benefit of this very large group of chemicals is that they make products water-resistant. PFAS can be found in everyday items like non-stick pans, fast food packaging, firefighting foams, and more. 

Now, scientists know that ingesting PFAS is bad news. But what’s really worrying in the case of menstrual underwear is that these chemicals were found in the moisture-wicking layer of the underwear – the part that sits right against the vagina. That raises some major red flags about the potential health impact of these panties since one study showed that a common PFAS, perfluorooctanoic acid (PFOA) does absorb through the skin. The only issue is that skin absorption of other PFAS is not well understood and requires more research studies.

So, that leaves us wondering: How on earth did PFAS make it into menstrual underwear?

How Did PFAS Get In The Period Panties?

Since PFAS can be used to create a waterproof layer, it’s safe to say that manufacturers added these chemicals intentionally in many cases.

The study found Thinx panties to have large amounts of the chemical (3,264 parts per million), making it clear that this was intentional.

In other cases, some brands like Saalt had 10 ppm of fluorine, which is a minimal amount. This might indicate that the PFAS are in the panties due to contamination somewhere during production.

Any amount of PFAS is unacceptable in a menstrual product, and we would not recommend any pair of period underwear containing any PFAS.

Update: Thinx Settled Their Class-Action Lawsuit (January 2023)

“Through its uniform, widespread, nationwide advertising campaign, [Thinx] has led consumers to believe that Thinx Underwear is a safe, healthy and sustainable choice for women, and that it is free of harmful chemicals. In reality, Thinx Underwear contains harmful chemicals … which are a safety hazard to the female body and the environment.”

Dickens vs. Thinx, INC.

As of January 2023, Thinx has settled a class-action lawsuit for $5,000,000. If you purchased a pair of the panties, you could be eligible to receive $7 per pair in damages or a wonderful coupon for 35% off another pair of PFAS-ridden panties from the brand if you wish. The company did add that they will “take measures to ensure the chemicals are not added to our products”.

Although the brand settled for $5M USD, a spokesperson said:

“The litigation against Thinx has been resolved, the settlement is not an admission of guilt or wrongdoing by Thinx, and we deny all allegations made in the lawsuit.”

Thinx Spokesperson

Are PFAS In Period Panties Unsafe?

It’s not clear how many PFAS in period panties might be dangerous. Researchers found some brands to have trace amounts (Saalt with 10ppm) while others had large amounts (Thinx with 3,264 ppm).

Because we don’t know the possible impact of these chemicals, we believe that any level of traceable PFAS should be avoided at all costs.

We recommend only those brands that studies found to have no PFAS whatsoever.

Certain PFAS have been linked to issues like:

• Lowering a woman’s chance of getting pregnant
• Interfering with the body’s natural hormones
• Increasing cholesterol levels
• Affecting the immune system
• Increasing the risks for some cancers
• Increasing the chance of miscarriage
• Affecting fetal and child development
• Increasing risk of asthma and allergies in children

This is a big deal. These menstrual panties are put in a sensitive area of the body, where they could very well be having negative health impacts that we don’t even know about, and they remain in the body for a prolonged period of time.

You Can’t Always Trust What Brands Tell You

No brand would say that they have PFAS in their underwear, and many that you look at will outright say that they don’t contain the chemical.

In the case of Thinx, they advertise their products as “nontoxic, harmless, sustainable, organic, and otherwise safe for women and the environment.”

Since so many brands claim to be free of PFAS, but only some were independently lab tested, we can only recommend those brands verified through testing to be free of PFAS.

The Lack of Consumer Protection Laws in Menstrual Products

There is a significant lack of consumer protection laws regarding feminine hygiene products. Only two states have such laws, and they’re not even in effect yet.

• California has enacted new laws that require expanded ingredient disclosure for feminine hygiene products, including period underwear. As of Jan 1st, 2023, The Menstrual Products Right to Know Act of 2020. (AB 1989) mandates that menstrual products sold in California must clearly and conspicuously list all ingredients used. However, this law only focuses on “intentionally added” ingredients and does not cover contaminants.
• New York has a similar law as of 2021, focusing on “intentionally added” ingredients. The Menstrual Products Right To Know Act (S2387B), championed by New York State Assembly Member Linda Rosenthal and signed by Governor Andrew Cuomo, forces brands to print a simple list of ingredients on all menstrual products.
• Federally, in September 2022, the Menstrual Products Right To Know Act of 2022 (H.R.8829) was introduced to the house, but as of the current date of writing (March 2023), there has been no progress on the bill.

It’s a fundamental right of women to know what ingredients might be in their menstrual products. We have a long way to go regarding mandated transparency for consumer protection, but these two laws are a good start.

However, because of the lack of laws, it’s easy to see how issues like PFAS in period underwear become a problem in the first place.

The Importance of Materials Used

Because panties (whether they’re period or regular) are worn in a very sensitive area, it’s important to wear those made from non-toxic materials.

We generally only recommend those made with organic cotton, although even non-organic cotton is better than synthetic materials like polyester or nylon.

• Cotton – The best material for reusable menstrual underwear. Ideally, organic cotton will be used.
• Bamboo viscose – A good, renewable and natural material. Bamboo cannot be certified as organic on a technicality – it grows in the wild and doesn’t need fertilizers.
• Polyester – Not recommended. Polyester is made from petrochemicals and is not breathable, which is a bad thing for a pair of underwear.
• Spandex / Elastane – Commonly used in the waistband to make it stretch. While this is a synthetic fiber, it’s used in virtually all underwear to make it stretch.

How We Compiled This Guide

We reached out to every brand on the list to ask them about important topics such as:

• What materials do the panties use?
• Do the panties have antimicrobial chemicals?
• What certifications do they have?
• How long do the panties last?
• And more

Menstrual Underwear Rated: Best

We found a total of 4 brands that tested as having zero PFAs through independent lab testing. We recommend these brands for this reason.

Period (Our Recommendation)

Click here to visit The Period Company’s website (Use code BG15 for 15% off of your order!)

Period’s menstrual underwear is 95% OEKO-TEX certified organic cotton and 5% polyester, don’t contain any antimicrobial chemicals, and are fairly inexpensive. They’re also the most affordable brand, at $6 per pair with the coupon. They we also independently lab tested and found absolutely no PFAs.

Material	95% organic cotton, 5% polyester
Lining Material	95% organic cotton with 5% spandex jersey
Antimicrobial chemicals	No
Absorbency	10 tampons worth
Lifetime	2-10 years
Certifications	OEKO-TEX
Styles	High waisted ($12), Bikini ($12), Sleeper ($14), Teen Boyshort ($12), Teen Bikini ($12), Adaptive Bikini ($12), Teen Adaptive Bikini ($12), Boxer ($12)
Sizes	XS-6XL

Modibodi

Website (Get $15 off your order with this link)

These period panties are made from 95% bamboo viscose and were independently lab tested where no PFAs were found.

Material	95% bamboo viscose, 5% spandex
Lining Material	Merino wool, polyester, polyamide
Antimicrobial chemicals	Modibodi uses an antimicrobial treatment that does not use nanotechnology. This treatment is registered with the Environmental Protection Authority to eliminate bacteria and odor
Absorbency	1-4 tampons worth
Lifetime	At least 2 years
Certifications	Not specified
Styles	Brief ($24-25), Boyshort ($30-34), Boyleg ($23-28), Bikini ($22-30), Full Brief ($25-33.50), Hi Waist Bikini ($26-33)
Sizes	XS – 6XL

Bambody

An independent lab study of Bambody’s underwear found no traceable amounts of PFAs. Using no antimicrobial chemicals and bamboo, we would prefer if the inner layer was cotton rather than synthetic materials, but we can still recommend them.

Website / FAQ

Material	Bamboo fabric, cotton, spandex
Lining Material	80% polyester, 20% nylon
Antimicrobial chemicals	None
Absorbency	6 tampons worth
Lifetime	18 months
Certifications	In the process of getting an OEKO-TEX certification
Styles	Absorbent Bikini ($14.90-26.90), Absorbent Boyshort ($14.90-36.90), Absorbent Hip Hugger ($14.90-34.90), Absorbent Hipster ($14.90-36.90), Absorbent Midi Brief ($14.90-36.90), Absorbent Panty ($14.90-39.90), Leakproof Bikini ($14.90-31.90)
Sizes	XXS – XXL

Luna Pads

Luna was found to have zero PFAs in the independent lab study, and since they offer panties that are certified organic cotton and have no antimicrobial chemicals, we recommend them.

Website / FAQ

Material	Depends on the underwear: Tencel™, Truetex™, recycled polyester, organic cotton, technical cotton, thermoplastic polyurethane
Lining Material	Truetex™ which is a blend of hydrophilic and hydrophobic fibers
Antimicrobial chemicals	None
Absorbency	1-4 tampons worth
Lifetime	3 years
Certifications	OEKO-TEX Standard 100
Styles	Boxer Brief ($46), Brief ($46), Bikini ($40), Hispter ($42), Thong ($32)
Sizes	XS – 5XL

Menstrual Underwear Rated: Good

Wuka

Wuka was not analyzed in the study, but they report in their FAQ that they regularly test for additional chemicals, including PFAs. They also don’t use any antimicrobial chemicals.

Website / FAQ

Material	natural bamboo material.Organic cotton, Tencel modal which are biodegradable fibers, econyl which is made from plastic waste from our oceans
Lining Material	Cotton/polyester blend, tencel modal or organic cotton.
Antimicrobial chemicals	None
Absorbency	4 tampons worth
Lifetime	2 years
Certifications	OEKO-TEX, GOTS
Styles	High Waist (£24.99-25.99), Midi Brief (£23.99-24.99), Seamless Midi Brief (£19.99-22.99), Bikini Brief (£17.99-21.99)
Sizes	XS – 3XL

Menstrual Underwear Rated: Iffy

These brands were not tested in the independent lab study. We recommend purchasing from brands that were verified to have no PFAs.

Love Luna

The independent lab study did not cover Love Luna’s underwear, so it’s unclear if they have PFAs or not.

Website / FAQ

Material	Depends on the underwear: cotton, elastane for full brief and the midi; microfibre – nylon, elastane for the bikini
Lining Material	100% cotton
Antimicrobial chemicals	None
Absorbency	2-4 tampons worth
Lifetime	The exact lifetime is not specified, but these undies can last several years
Certifications	OEKO-TEX
Styles	Bamboo Brief (AU$20), Full Brief (AU$15), Midi Brief ($AU15), Bikini Brief ($AU15), Teens Bikini ($AU15), Teens Shortie ($AU15)
Sizes	S – 2XL

Dear Kate

Website / FAQ

These period panties are made of synthetic materials, contain antimicrobial compounds, and are expensive for panties made of synthetic materials. Not recommended.

Material	74% nylon, 26% lycra
Lining Material	90% micro-polyester, 10% spandex
Antimicrobial chemicals	Silver salt compound
Absorbency	1-4 tampons worth
Lifetime	Unspecified
Certifications	None
Styles	Hipster ($38-40), Briefs ($46), Thongs ($34)
Sizes	XS – 3XL

Tom Organic

Tom Organic wasn’t included in the study, and they make no claims at all about PFAs. For these reasons, we can’t recommend them.

Website / FAQ

Material	95% Organic cotton, 5% elastane
Lining Material	Cotton, polyester
Antimicrobial chemicals	None
Absorbency	2 tampons worth
Lifetime	Approximately 40 washes
Certifications	GOTS, Australian Organic Standard
Styles	Period Briefs ($15)
Sizes	XXS – 3XL

Get Rael

Rael was not included in the independent study. Because we can’t verify that they have no PFAs, we can’t recommend them.

Website / FAQ

Material	OCS, USDA certified and non-GMO cotton
Lining Material	100% cotton absorbency layer
Antimicrobial chemicals	Not specified
Absorbency	3 tampons worth
Lifetime	The exact lifetime is not specified, but these undies can last several years
Certifications	Not specified
Styles	Period Underwear ($20)
Sizes	S – XL

Menstrual Underwear Rated: Bad

These brands were lab tested and verified to contain PFAs. For this reason, we strongly recommend avoiding them.

Knix

Website

Knix High Rise underwear was lab tested where they found 373 ppm flourine. It’s unknown what level of fluorine is safe, but because other brands tested at 0 ppm flourine, we can’t recommend this brand.

Material	Depends on underwear: 77% nylon, 23% lycra for CoreLove and leakproof undies; 47% cotton, 47% modal, 6% spandex for for cotton modal undies
Lining Material	86% cotton, 10% spandex, 4% carbon
Antimicrobial chemicals	Knix uses natural moisture-wicking and antimicrobial materials in the gusset liner, which helps prevent yeast infections and inhibits the growth of bacteria
Absorbency	1-8 tampons worth
Lifetime	8-12 months
Certifications	OEKO-TEX
Styles	Bikini ($23-30), High Rise ($28-35), Thong ($23-30), Dream Short ($38), Boyshort ($23-30), Cheeky ($23-30), Cotton Modal Super Leakproof High Rise ($35), Cotton Modal Super Leakproof Bikini ($30), Core Love High Rise ($36)
Sizes	XS – 4XL

Thinx

Website / FAQ

Thinx panties were independently lab tested (Boyshort, High Waist and BTWN) and each of them were found to have 619 ppm, 940 ppm, and 132 ppm fluorine respectively. While it’s unknown what amount of fluorine is safe, the fact that they have detectable fluorine makes us unable to recommend them.

Material	Depends on underwear: 89% nylon, 11% elastane for classic undies; 95% organic cotton, 5% elastane for organic cotton undies; 78% polyamide, 22% elastane for air undies
Lining Material	Depends on underwear: 100% polyester and middle breathable PUL for classic undies; 95% cotton, 5% elastane, middle breathable PUL for organic cotton and air undies
Antimicrobial chemicals	The wicking layer has an application of non-migratory silver to control odor and the spread of bacteria
Absorbency	3-5 tampons worth
Lifetime	Not specified
Certifications	OEKO-TEX Standard 100
Styles	Super Hiphugger ($39), Hiphugger ($32-34), Boyshort ($39), Sport ($23), Hi Waist ($38-42), French Cut ($35), Cheeky ($30), Thong ($24), Brief ($34-39), Bikini ($32), Sleep Shorts ($50), Leggings ($95), Training Shorts ($65), Cycle Shorts ($75), Leotard ($75)
Sizes	XXS – 3XL

Ruby Love

An independent study of Ruby Love’s underwear found 27 ppm of flourine. While this is a small amount compared to other brands, it’s enough that we cannot recommend them.

Website

Material	80% interlock twisted yarn cotton, 20% spandex
Lining Material	Interlock twisted yarn cotton
Antimicrobial chemicals	Not specified
Absorbency	2-6 tampons worth
Lifetime	2-3 years
Certifications	None
Styles	Bikini ($19.99), Hipster ($19.99), Brief ($22.99), High Waist ($24.99), Seamless ($24.99)
Sizes	XS – 3XL

Saalt

The independent study found 10 ppm of fluorine in Saalt’s period panties. They’re also made from polyester, and for both of these reasons, we cannot recommend them.

Website / FAQ

Material	80% recycled polyester, 20% elastane
Lining Material	92% recycled polyester, 8% spandex
Antimicrobial chemicals	Not specified
Absorbency	1-3 tampons worth
Lifetime	The exact lifetime is not specified, but these undies can last several years
Certifications	OEKO-TEX
Styles	High Waist Brief ($39), Mesh Hipster (%36), Lace Hipster ($36), Bikini ($34), Thong ($29)
Sizes	XS – XXL

Sustain

71 ppm & 17 ppm fluorine were found in Sustain panties. This is a small amount, but since some brands were found to have zero PFAs, we can’t recommend these.

Website

Material	95% organic cotton, 5% spandex
Lining Material	Polyurethane laminate topped with 100% organic cotton
Antimicrobial chemicals	None
Absorbency	1 tampon worth
Lifetime	2-3 years
Certifications	OEKO-TEX Standard 100, GOTS
Styles	Period Underwear ($29.95)
Sizes	XS – XL

In Conclusion

Only four brands were verified not to have any PFAs. These brands are: Period, Luna Pads, Modibodi, and Bambody.

We Recommend The Period Company

Our recommendation is Period.co (Use code BG15 for 15% off of your order) – they were 100% PFAs free, use no microbial chemicals, are made from 95% organic cotton, and are OEKO-TEX certified. They’re also the most affordable brand at only $6 per pair with coupon. Click here to see their full range of non-toxic menstrual underwear.