Is Period Underwear Safe? What to Know and How to Choose One

You might have heard about people who wear period underwear for collecting menstrual flow. But is it a better choice than a pad or a tampon?

There may be benefits to using period underwear. Wearing underwear seems more comfortable than worrying about a pad staying in place all day and easier than inserting a tampon. But some people are concerned about chemical exposure and whether period underwear is more difficult to dispose of.

Let’s find out if this product is safe and what you should look for when choosing a pair.

Does period underwear contain harmful chemicals?

It’s not clear.

Some brands of period underwear were found to contain chemicals called PFAS (perfluoroalkyl and polyfluoroalkyl substances) on their inner absorbent and outer layers. PFAS are chemicals made by humans. They are found in many everyday products and have drawn attention because they may affect human health.

Some studies have found that people exposed to high levels of these chemicals were more likely to develop:

• Kidney or testicular cancer

• Preeclampsia or high blood pressure during pregnancy

• Increased cholesterol levels

• Liver inflammation

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But researchers don’t fully understand how PFAS can affect humans. Most studies that show negative health effects involve animals. In those studies, animals were exposed to very high levels of PFAS. It’s not clear how these results translate to humans who are exposed to much lower levels of PFAS in everyday life.

One problem with PFAS is that they don’t break down when you throw them away. They live in the environment forever, so they build up and get into food and water supplies. From there, they get into people’s bodies. Over time, the levels inside people build up too.

Low exposure to PFAS from one product may not cause direct harm, but the same can’t be said for a lifetime of exposure. Scientists are still trying to determine if there is a safe level of PFAS exposure for humans.

Period underwear lawsuit

People who bought Thinx menstrual underwear sued the company in January 2021, alleging that it was not up front about the PFAS in the product. Thinx settled the class-action lawsuit in January 2023.

Thinx also said that in the future, PFAS will not be added to products intentionally. But the lawsuit was enough to get people thinking about whether period underwear is safe.

Do gynecologists recommend period underwear?

There is no consensus on the use of period underwear, but the American College of Obstetricians and Gynecologists says it is OK to use. Kelly Johnson-Arbor, a medical toxicologist, says period underwear is mostly safe because it’s worn for a short period of time.

Keep in mind that many menstrual products, including period underwear, do not require FDA approval.

Is there nontoxic period underwear?

It might be hard to tell if your period underwear is PFAS free. Some companies state that their products are not treated with PFAS. Others have submitted their products to independent labs to verify that their products are PFAS free.

But no regulatory body is testing period underwear. That makes it hard for any brand to guarantee that its products are nontoxic. Still, many companies take safety seriously and do their best to disclose the ingredients in their products and assure people that their products are safe.

You can always contact a company if you have questions about a product’s safety.

What to look for when buying period underwear

Your health is important, and you should feel empowered to question if a product is safe. When shopping for period underwear, here are some things to look for:

• Underwear made from natural materials (like cotton and bamboo viscose), rather than synthetic ones (like polyester or nylon): Natural materials are biodegradable, meaning they break down in the environment over time. Natural fibers are also more breathable and less likely to irritate your skin.

• Longer-lasting products: You can wash period underwear and reuse them for months to years. Check the label for the expected life span of your underwear. Using less detergent can help the environment and save you money.

• Products that come in a variety of styles, sizes, and prices: This will help you find the right one for your needs.

Some other tips for using period underwear:

• Change them after 8 to 12 hours. Some period underwear is labeled “high absorbency,” but it’s best to change your underwear after 8 to 12 hours. Bacteria can build up in menstrual products, so experts recommend changing them regularly.

• Have a backup available. If you run out of underwear, you’ll need backup products. If you have a heavy menstrual flow, you can use pads, tampons, or menstrual cups along with your period underwear.

Why trust our experts?

Written by:

Jasmine Jackson

Jasmine has worked as a production editor, proofreader, and writer. She is a certified yoga instructor, aerial yoga instructor, and stretch therapist.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

Reviewed by:

Adriena Beatty D.O., MBA, CPE

Adriena Beatty, DO, MBA, CPE, is an Army veteran and board-certified obstetrician and gynecologist with over 20 years of experience. She is a graduate from Tuskegee University with a degree in chemical engineering and chemistry.

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