Sexual & Reproductive Health Products The 12 Best Period Underwear of 2023, Tested and Reviewed These pairs provide absorption and comfort, even on heavy days. By Nicole Crawford Nicole Crawford Nicole has been a health and wellness writer and editor for over a decade, and has also worked with clients as a personal trainer, yoga instructor, and birth/postpartum doula. What she loves most: raising her six kids, running, and making nourishing, tasty meals for her family. Learn about our editorial process Updated on May 17, 2023 Medically reviewed by Peter Weiss, MD Medically reviewed by Peter Weiss, MD Peter Weiss, MD, is a board-certified OB/GYN and expert in women's health. Learn about our Medical Expert Board Fact checked by Rich Scherr Fact checked by Rich Scherr Rich Scherr is a seasoned journalist who has covered technology, finance, sports, and lifestyle. Learn about our editorial process Print We independently evaluate all recommended products and services. If you click on links we provide, we may receive compensation. Learn more. Courtesy of Merchants / Photo Illustration by Kevin Liang for Verywell Health Period underwear allows you to manage that time of the month without worrying about pads, tampons, or menstrual cups. They're designed with two priorities in mind: comfort and convenience. So how do they work? It’s a pretty simple concept. Basically, period underwear is normal underwear with a pad or gusset. The gusset is made of absorbent fabric, which catches period blood and wicks it away from your skin to keep you dry. According to Dr. Staci Tanouye, an OBGYN who works in private practice in Jacksonville, Florida, “Period underwear is great for people who don’t want to wear pads or tampons at all and also great as a backup to tampons or cups.” Like tampons, pads, and cups, period underwear is rated based on how much blood it can absorb, so you’ll see the typical “light,” “medium,” and “super” labels when you shop around. Period underwear might seem expensive, but when you consider that it can replace pads, cups, and tampons in the long term, the investment is worth it. “They can be a cheaper option than disposable period products over the long term,” said Tanouye. “They can also be more environmentally friendly than single-use disposable products for the same reason.” To find the best period underwear, our testing team at the Verywell Lab sampled 46 of the highest-rated pairs on the market and rated them based on their absorbency, comfort, and value. We also reached out to OBGYN doctors to get their recommendations for finding the best period underwear for your specific menstrual needs. Verywell Health FYI Thinx recently settled a lawsuit (Dickens, et al. v. Thinx Inc.) surrounding the presence of per- and poly-fluoroalkyl substances (PFAS) and silver nanoparticles, which were found in multiple styles of the brand’s underwear following independent testing. The suit alleges that the presence of these chemicals goes against the brand’s advertising as free of harmful chemicals and toxic metals. After speaking to doctors and conducting research to find out more about how the presence of PFAS in period underwear can affect consumers, we've decided to continue to include Thinx period underwear on our list. You can read more about PFAS and period underwear in our "Frequently Asked Questions" section below. Our Top Picks Best Overall: Thinx For All Super Absorbency Brief at Walmart Jump to Review Best Budget: American Eagle Aerie Real. Period. Underwear at Ae.com Jump to Review Best for Heavy Flow: Goat Union Overnight Period Underwear at Amazon Jump to Review Best Thong: Hamilton Beach Toastation Oven at Amazon Jump to Review Best Comfort: Cora Period Underwear at Amazon Jump to Review Best Plus Size: TomboyX First Line Leakproof Bikini at Amazon Jump to Review Best Seamless: The Eco Woman Seamless EcoPanties at Theecowoman.com Jump to Review Best Cotton: Rael Reusable Period Underwear at Amazon Jump to Review Best Lingerie: Dear Kate Ada Full Brief at Dearkates.com Jump to Review Best for Light Flow: Knix Medium Absorbency Leakproof Boyshort at Knix Jump to Review In This Article Expand Our Picks How We Tested We Also Tested What to Look For FAQ Why Trust Verywell Health Best Overall Thinx For All Super Absorbency Brief 5 Target View On Walmart View On Target View On Thinx.com Our Ratings Absorbency 4.5/5 Feel 5/5 Value 5/5 Pros Absorbent Great value Stretchy and comfortable Cons Limited coverage in the back We rated Thinx For All Women’s Super Absorbency Brief period underwear a perfect 5 for overall value and comfort. This period underwear also features amazing absorbency (five tampons or 2.5 pads worth). If you need period underwear with super absorbency, you won’t be disappointed. However, this underwear is so comfortable that it’s also a great choice for light and medium-flow days. Thinx underwear features a comfortable mid-rise waist. Our tester noted the fabric is also very soft. “It has a nice cottony feel,” she said. “The gusset is kind of like a soft washcloth, and it is much thicker than many of the others we've tested.” Made of 95% cotton and 5% elastane, the underwear is easy to wash (machine wash cold), and it dries quickly. The only downside is that there isn’t as much coverage in the back as some other pairs we tried. Other than that, at just $17 per pair, this underwear definitely tops our list for comfort, absorbency, and affordability. Price at time of publication: $17 Key Specs:Absorbency: Super | Material: Cotton, elastane | Fit: Mid-rise | Sizes: XS - 4X | Care Instructions: Machine wash, lay flat to dry/line dry Verywell Health / Leticia Almeida Verywell Health /Leticia Almeida Verywell Health /Leticia Almeida Best Budget American Eagle Aerie Real. Period. Underwear American Eagle View On Ae.com Pros Great for light flow days Gusset goes very high in back Comfortable waistband Cons Don’t hold very much liquid If you’re on a budget, American Eagle’s Real. Period. Underwear is an affordable option for lighter flow days. The fabric is comfortable and breathable, and the gusset absorbed the advertised amount of liquid. “The jersey fabric is soft to the touch but feels thick, so it might be uncomfortable under tighter pants, like jeans,” noted our tester. “The gusset is quite thick as well and reaches nearly all the way up to the back of the underwear.” The downside is the gusset only absorbs about two tampons worth of period blood. But despite the low amount of fluid these undies absorb, the price tag makes them a no-brainer for low-flow days toward the end of your period. The fabric blend of cotton, acrylic, polyester, and elastane washes easily in the washing machine, and you can also tumble dry on low in the dryer. Price at time of publication: $10 Key Specs:Absorbency: Light-medium | Material: Cotton, acrylic, polyester, elastane | Fit: Boybrief/regular rise | Sizes: XXS - XXL | Care Instructions: Machine wash delicate, tumble dry low Verywell Health / Leticia Almeida Verywell Health / Leticia Almeida Verywell Health / Jhett Thompson Best for Heavy Flow Goat Union Overnight Period Underwear 4.2 Amazon View On Amazon View On Goatunion.com Our Ratings Absorbency 4/5 Feel 3/5 Value 4/5 Pros Great absorption Affordable price Wide range of sizes Cons High waist might not be comfortable for everyone For heavy flow days or overnight use, Goat Union Overnight Period Underwear topped our list. Goat Union claims their underwear can absorb 6 teaspoons of fluid, and this claim held up to our testing. “These absorbed slowly but did absorb,” noted our tester. “The gusset was wet, but the exterior was dry. There was no overspill.” The moisture-wicking bamboo fabric and four-layer design keep you feeling comfortable even during the heaviest flow. Although the high waist and gusset in the front and back are ideal for those looking for a lot of coverage, our tester noted there were some uncomfortable seams that kept her from giving these a perfect rating. The fabric was thick and soft. The underwear had a ton of seams everywhere, which does not feel great, especially if you're not into seams.” Nevertheless, when you consider the dependable absorbency and affordable price point of this underwear, it still comes out a winner. Price at time of publication: $17 Key Specs:Absorbency: Light-heavy | Material: Bamboo, cotton, polyester, nylon, spandex | Fit: Brief | Sizes: XS - 5X | Care Instructions: Machine wash cold, gentle cycle, tumble dry extra-low or hang dry Verywell Health / Jhett Thompson Verywell Health / Leticia Almeida Best Thong Hamilton Beach Toastation Oven With 2-Slice Toaster Combo Courtesy of Amazon.com. View On Amazon Pros Comfortable Absorbs advertised amount of fluid Cons Only for light days We were a bit skeptical of the idea of an absorbent thong, but this product surprised us. It’s definitely not for heavy flow days, but as our tester noted, “If you're that rare person who likes to wear thongs while you have your period, and most importantly, you have a very light flow, I would absolutely recommend it.” It absorbed 1 teaspoon of fluid during our test without any leakage, which is exactly what it’s advertised to do. The thong is seamless and made from a soft, comfortable blend of nylon for the body and cotton/spandex for the gusset. The gusset also features a layer of polyester to provide extra waterproof protection. Our tester summed it up: “This thong absorbed water quickly, with no spillover, and the outer gusset stayed dry. I can't believe I'm saying this about a thong, but wow!” Price at time of publication: $20 Key Specs:Absorbency: Light | Material: Nylon, cotton, polyester, spandex | Fit: Thong| Sizes: XS - XXXXL | Care Instructions: Machine wash cold, lay flat to dry Verywell Health / Jhett Thompson Verywell Health / Leticia Almeida Best Comfort Cora Period Underwear 4.9 Target View On Amazon View On Walmart View On Cora.life Our Ratings Absorbency 4.5/5 Feel 5/5 Value 5/5 Pros Soft,comfortable fabric Amazing absorbency Claims to be free of PFAS or azo dyes Cons Not much coverage in the back Not as many sizes as other brands Cora period underwear absorbs the equivalent of three tampons’ worth of period blood, making them a great option for moderate flow. The bikini-style underwear is 100% cotton throughout, with a bit of elastane to add some stretch. “[It has a] thick elastic waistband with a firm gusset that feels a bit like a pad, but without really visible seams like some of the other options. The gusset coverage is decent but not as high in the back as some others,” said our tester. Cora prides itself on brand sustainability and responsibility. For every product purchased, the company donates products and educational resources to BIPOC communities. According to the company, their period underwear is also made without any PFAS or azo dyes. Price at time of publication: $25 Key Specs:Absorbency: Moderate | Material: Cotton, polyester, elastane | Fit: Bikini | Sizes: XS - XXL | Care Instructions: Machine wash delicate, lay flat to dry or line dry Verywell Health / Jhett Thompson Verywell Health / Leticia Almeida Best Plus Size TomboyX First Line Leakproof Bikini 4.9 TomboyX View On Amazon View On Nordstrom View On Tomboyx.com Our Ratings Absorbency 4.5/5 Feel 5/5 Value 5/5 Pros Very leak-proof Oeko-Tex Standard 100 Certified Good range of sizes Cons Doesn’t absorb advertised amount TOMBOYX First LIne Leakproof Bikini Period Underwear is available in a wide range of sizes, from 3XS to 6X. The fabric does an amazing job absorbing fluid and repelling odors, and it’s also Oeko-Tex Standard 100 Certified, meaning it does not contain any known toxic chemicals (including those in the PFAS family). “I would wear these to sleep or workout because they would likely stay up, no rolling,” noted our tester. “The waistband is cool-looking too.” The underwear is marketed as a good option for light flow, but the website also claims it absorbs 8 teaspoons of period blood. Our tester noted the gusset absorbed 6 teaspoons with no leakage, which would make this period underwear a good choice for moderate to heavy flow days. Price at time of publication: $25 Key Specs:Absorbency: Light/moderate | Material: Cotton, polyester, spandex | Fit: Bikini | Sizes: 3XS - 6X | Care Instructions: Machine wash cold in mesh bag, line dry Verywell Health / Jhett Thompson Verywell Health / Leticia Almeida Verywell Health / Leticia Almeida Verywell Health / Leticia Almeida Best Seamless The Eco Woman Seamless EcoPanties 4.9 The Eco Woman View On Theecowoman.com Our Ratings Absorbency 4.5/5 Feel 5/5 Value 5/5 Pros Oeko-Tex Standard 100 Certified Great absorption Cons Slightly longer washing process than other pairs The Eco Woman EcoPanties Seamless underwear is a solution for those who prefer not to feel all the seams all the time. Made from bamboo, cotton, spandex, and polyester, this underwear also features a waterproof PUL layer to keep moisture at bay. Eco Woman EcoPanties are also made of Oeko-Tex Standard 100 Certified fabric. Despite the fact that it’s a seamless option, the gusset held 4 teaspoons of liquid with no spillage. And it’s comfortable, too, as our tester said: “The best part was that the interior gusset seams felt dry to slightly damp—unlike any of the others I tested. The exterior fabric felt completely dry, too.” Price at time of publication: $19 Key Specs:Absorbency: Light/moderate | Material: Bamboo, cotton, polyester, spandex | Fit: Bikini | Sizes: 3XS - 6X | Care Instructions: Cold rinse, machine or hand wash cold, line dry Verywell Health / Jhett Thompson Verywell Health / Leticia Almeida Verywell Health / Leticia Almeida Verywell Health / Leticia Almeida Best Cotton Rael Reusable Period Underwear 4.7 Nordstrom View On Amazon View On Getrael.com View On Jcpenney.com Our Ratings Absorbency 5/5 Feel 4/5 Value 5/5 Pros Great value Outside stays dry Cons Runs on the small side Only four size options When it comes to a balance of comfort and absorption, cotton is a hard fabric to beat. If you’re a cotton lover, Rael Reusable Period Underwear should be at the top of your list. The underwear is 95% cotton, with a small amount of spandex for stretchiness. The gusset is 95% rayon for an extra absorption boost. The underwear also features a leak-proof polyester barrier to keep you dry. This underwear isn’t as stretchy or soft as some of the other products we tried, and according to the manufacturer, it also runs on the small side. (Of course, if you’re used to purchasing products that are primarily cotton, those are both qualities you’d expect.) “It absorbed 3 teaspoons easily,” our tester said. “The outside was dry but cool to the touch.” The underwear also comes with a handy reusable pouch for machine washing. Just be sure to do a pre-rinse before the main wash. Price at time of publication: $20 Key Specs:Absorbency: Light/moderate | Material: Cotton, rayon polyester, spandex | Fit: Bikini | Sizes: XS - XL | Care Instructions: Cold rinse, machine wash cold, line dry or lay flat to dry Verywell Health / Jhett Thompson Verywell Health / Leticia Almeida Verywell Health / Leticia Almeida Verywell Health / Leticia Almeida Verywell Health / Leticia Almeida Best Lingerie Dear Kate Ada Full Brief 4.9 Dear Kate. View On Dearkates.com Our Ratings Absorbency 5/5 Feel 5/5 Value 4.5/5 Pros Soft material Full coverage Cons High-rise waist isn’t for everyone Thanks to these Dear Kate Ada Briefs, you can still feel sexy during your period. The underwear features an attractive, durable lace waistband, flattering rise, and three breathable layers of absorbent fabric that will keep you dry. Dear Kate lists the absorbency for these panties as 3 teaspoons, but our tester found they held more than that. “I tested an extra 2 teaspoons of liquid, and they held the full 5 teaspoons without leaking,” she said. “The outside of the panty stayed dry. With 3 teaspoons, there was some transfer from the inside, but not much.” This product is also free of PUL, making it a great option if you’re trying to decrease your exposure. Price at time of publication: $46 Key Specs:Absorbency: Light/moderate | Material: Nylon, micropolyester, polyester, elastane | Fit: High-rise | Sizes: XS - 3X | Care Instructions: Machine wash cold (do not use fabric softener), line dry Verywell Health / Jhett Thompson Verywell Health / Leticia Almeida Best for Light Flow Knix Medium Absorbency Leakproof Boyshort 4.2 Knix View On Knix Our Ratings Absorbency 3.5/5 Feel 5/5 Value 3/5 Pros No leakage Great for teens Cons Minimal amount of fluid transfer Knix Leakproof Boyshorts absorbed the advertised amount of 3 teaspoons very quickly, with no leakage and a minimal amount of transfer, making it a good option if you have a light or moderate flow. “Great for teens. It's simple, nice, feels great against your skin, and has no annoying tags,” our tester said. “I would get this if I had a teen or tween daughter who had just started her period and wanted to feel comfortable handling it—and had a light flow.” This underwear is also extremely comfortable, so if you have a heavy flow and are looking for a backup pair that fits like a “second skin” (our tester’s words!), check these out. Price at time of publication: $22 Key Specs:Absorbency: Light/moderate | Material: Nylon, Lycra, cotton, spandex, carbon, polyester | Fit: Boyshort | Sizes: XS - XXXXL | Care Instructions: Machine wash cold with mild detergent (no bleach), lay flat to dry Verywell Health / Jhett Thompson Verywell Health / Leticia Almeida Verywell Health / Leticia Almeida Best for Exercise Thinx Cycle Shorts 4.2 Amazon View On Amazon Our Ratings Absorbency 3/5 Feel 5/5 Value 4/5 Pros Soft fabric Lots of pockets Breathable fabric Cons Not for heavy flow Thinx Cycle Shorts are our choice for the best exercise period underwear. Not only do they absorb the advertised amount of period blood (about 3 teaspoons, or light flow), but they are also incredibly comfortable, making them a great choice for long workouts. They also feature several deep pockets where you can store small items if you’re on a long bike ride or run. “If you're working out or want to wear cozy athleisure toward the end of your period, or as added protection with a menstrual cup or tampon, I would definitely recommend these for the comfortable feel of the biker shorts,” our tester said. Price at time of publication: $75 Key Specs:Absorbency: | Material: Nylon, Lycra, cotton, spandex, carbon, polyester| Fit: Boyshort | Sizes: XS - XL | Care Instructions: Machine wash cold with mild detergent (no bleach), lay flat to dry Verywell Health / Jhett Thompson Verywell Health / Leticia Almeida Verywell Health / Leticia Almeida Best for Sleep Thinx Period Pajama Sleep Shorts 4.4 Thinx View On Amazon View On Thinx.com Our Ratings Absorbency 4/5 Feel 4.5/5 Value 4/5 Pros Super absorbent Comfortable Cute design Cons Small amount of gusset transfer You’ll get a great night’s sleep in Thinx Period Pajama Sleep Shorts due to their dependable absorbency and amazing comfort. The shorts feature built-in underwear with an absorbent gusset, but from the outside, they look like a normal pair of pajama shorts. Rated for super absorbency, these shorts held five tampons, or 8 teaspoons, of liquid in our testing. Although there was a little bit of fluid transfer on the gusset, our tester noted that the exterior remained completely dry. Comfort is also a key feature. “They're quite heavy and thick, but the gusset feels almost like terrycloth. The shorts feel nice and soft,” said our tester. "The gusset padding goes fairly high up the back and the front, good if you move around in your sleep.” The pockets and buttons also add a stylish flair. Our tester suggested these would be great items for postpartum use. Price at time of publication: $50 Key Specs:Absorbency: Super | Material: Modal, cotton, polyester, elastane | Fit: Short with built-in bikini underwear | Sizes: XS - 4X | Care Instructions: Hand wash or machine wash cold, delicate, hang dry Verywell Health / Jhett Thompson Verywell Health / Leticia Almeida Verywell Health / Leticia Almeida How We Rated the Best Period Underwear 4.8 to 5 stars: These are the best period underwear we reviewed. We recommend them without reservation.4.5 to 4.7 stars: These period underwear are excellent—they might have minor flaws, but we still recommend them.4.0 to 4.5 stars: We think these are great period underwear, but others are better.3.5 to 3.9 stars: These period underwear are just average.3.4 and below: We don't recommend period underwear with this rating; you won't find any on our list. How We Tested the Best Period Underwear Our period underwear testing was conducted in the Verywell Lab, with over 46 products under review. We consulted with several experts, including: Adi Katz, MD, FACOG, director of gynecology and director of the obstetrics and gynecology residency program at Lenox Hill Hospital Susan S. Khalil, MD, director of the Division of Sexual Health in Obstetrics, Gynecology, and Reproductive Science at the Icahn School of Medicine at Mount Sinai Leena Nathan, MD, an OBGYN in Westlake Village, California Staci Tanouye, MD, FACOG, an OBGYN who works in private practice in Jacksonville, Florida Nicole Williams, MD, a gynecologic surgeon based in Chicago Our testers first evaluated the absorbency of each pair of underwear by pouring the maximum advertised amount of liquid onto the gusset. They noted how well the underwear absorbed the liquid, rating each pair on a scale of one to five. Next, the team conducted a simple test with dry filter paper to determine whether or not the underwear had any leakage or fluid transfer issues. Testers held the filter paper against the underwear for 30 seconds and noted any changes in moisture, texture, or appearance. The third step was to wash each pair of underwear according to instructions with mild, unscented, dye-free detergent. The testers noted staining, residual odor, and the overall state of the underwear after washing. Testers also rated each pair of underwear based on feel and comfort. They noted whether the gusset felt overly wet, how the fabric felt against their skin, and any discomfort they felt due to seams or other design issues. The team concluded their testing by rating each pair of underwear based on value. Testers did not view the prices until after the other attributes had been assessed in order to maintain an unbiased view of each pair of underwear. The biggest limitation to our testing was time, but we are already working on another round of testing. This time, we’ll analyze how these selections hold up over time and with frequent washing. Stay tuned! Period Underwear We Also Tested If you have a heavy flow and are looking for leggings to provide extra support during workouts or yoga sessions, Knix Leakstrong Leakproof Leggings are an option you should consider. Just make sure you have a tampon, cup, or pad for backup since our tester found these lacking in the solo absorbency department. For a sporty fit that can hold up to lighter flow days, Neione Sporty Period Underwear is a comfortable option. Our tester knocked off a few points for some liquid transfer on the inner fabric (although the exterior remained dry). Proof Leak Proof High Waisted Briefs held 3 to 6 teaspoons of fluid in our testing, making them a great choice for moderate flow days. They’re also a stylish option with a durable lace waist and slimming high waistline. Though they’re not quite heavy-duty enough for heavy flow days, PINK Period Hipster Underwear was rated high for comfort and value. Our tester noted the gusset was a little stiff, and there was a bit of transfer to the interior fabric, which is why this pair didn’t make our top picks. We would be remiss if we failed to mention Aisle Leakproof Period BOOST Boxers due to their comfort, unique design, and amazing absorption. They didn’t quite hold the advertised amount of 8 teaspoons of fluid, though. What to Look for in Period Underwear Absorbency Just like pads and tampons, period underwear is rated for light, moderate, heavy, or super flow. Manufacturers usually note how many tampons or pads each pair will absorb. A normal tampon or pad can hold approximately 1 teaspoon of blood or 5 milliliters. If you have heavy bleeding, it might take some trial and error to select the best pair of period underwear. “People with heavy periods may have to experiment with various types of period underwear to see if the absorbency is enough for them,” said Tanouye. “Many brands advertise that they can contain as much as two to three tampons-worth. However, it may be most comfortable to use period underwear as a backup to either a tampon or cup if you will be outside of the home for a long period of time or without access to being able to change if needed.” Fit and Comfort Period underwear comes in a variety of styles, from boy shorts to thongs, to bikini styles. You’ll get the most bang for your buck if you consider what style you prefer. Regardless of the specific style you prefer, Tanouye noted that snug-fitting period underwear is best since it decreases leaks. You’ll also need to consider what kind of fabric and design you prefer. For example, some fabrics are stretchier, while others are less elastic. If you prefer seamless underwear, that is another feature to look for in your period underwear. Finally, consider your typical daily activities. Period underwear that is designed to absorb heavy flow during a long workout or jog might be overkill if you have a light flow and aren’t moving around a lot during the day. Material When it comes to fabric, period underwear isn’t as straightforward as regular underwear. You’ll need to consider both the body material and the gusset material when you’re choosing the best pair for you. “Period underwear is typically made of three layers: a top soft layer that is against the vulva and moisture wicking either a cotton or polyester tech fabric; a middle absorbent layer that is typically a microfiber super absorbent fabric—this can be very variable and made of a base of cotton, bamboo, wool, or similar; and a bottom/outer waterproof layer that is usually some kind of polyurethane fabric,” said Tanouye. If you are allergic to any of these materials, or if you don’t like the feel of them, be sure to check the list of materials before you make a purchase. Quality A high-quality pair of period underwear won’t just absorb more—it will also last longer and hold up in the wash. Additionally, as Tanouye said, higher-quality underwear can prevent skin irritation. “The quality of the moisture-wicking top layer is important,” she said. “One of the challenges I’ve found with period underwear is keeping the vulva as dry as possible as moisture can lead to skin irritation.” High-quality construction and materials help prevent these problems by keeping the skin dry and minimizing contact with the skin. Frequently Asked Questions Can period panties replace pads? Period panties replacing the need for pads will largely depend on someone’s specific period flow and how heavy it can get. “While it is unlikely that period panties can replace a pad on your heaviest day, they will probably work pretty well for the tapering off days,” said Nicole Williams, MD, a gynecologic surgeon based in Chicago. But periods can differ depending on the woman. So for some, period panties would likely replace the need for menstrual pads, cups, and tampons.While they won't replace pads entirely, they can help those who just started their period and aren't ready to transition to other period products. “It is a great option for adolescents who may not feel comfortable with inserting a tampon or menstrual cup and don't want to deal with the hassle of wearing a pad,” said Leena Nathan, MD, who works in Westlake Village, California. How do period panties work? How exactly period panties work largely depends on the company because each brand uses different types of material to get similar results. “It appears that period panties have many layers of absorbent material which seem to wick away any fluid and keep it inside the panty,” Williams said. The outer layer of the panty will most likely be made of material similar to what someone is used to wearing with their normal undergarments. The inner portion, on the other hand, is usually made of other materials to help absorb and store your period flow. How often should you change your period panties? The duration someone wears the undergarments will again likely depend on how heavy their flow is and what day they're on within their period. “While many of the manufacturers say between eight to 12 hours, I advise my patients to change their period panties to their level of comfort,” Dr. Williams said. “If you have a light flow, you may wear them like normal underwear for up to an entire day. If your flow is heavier, you may need a spare pair or two.”On heavier days, period panties can also be paired with a tampon or pad to last longer throughout the day. “If women know that they can have a heavy flow and need to change their pads or tampons every four to six hours or sooner, it would be a good idea to use a pad or tampon in addition to the period panties,” Dr. Nathan said. How long can you wear period underwear? How long one pair of period underwear lasts depends on your flow each day. The panties come in different flow levels, and if your flow is lighter, one pair of underwear may last eight hours or more. With a heavier flow, you may need to change your period underwear a few times throughout the day. Should I be concerned about PFAS in period underwear? PFAS are synthetic chemicals used to make products non-stick and waterproof and are common within the environment and our bodies. Because they take thousands of years to break down, they've become known as "forever chemicals," according to the Environmental Working Group. PFAS may impact fertility and increase the risk of certain cancers, including kidney and ovarian.Because of a class-action settlement by Thinx that alleged PFAS were found in their products, many people are worried about the impact of these chemicals in period underwear.The OBGYNs and researchers we spoke to agreed that we are exposed to PFAS so often on a daily basis that using period underwear for a few days every month may not pose any additional risks to our health. "People are exposed to PFAS daily in the air we breathe, the water we drink, and the food we eat. It's impossible for us to avoid PFAS exposure in our daily lives. We don't need to be alarmed about the potential for health effects due to the use of Thinx products," Kelly Johnson-Arbor, MD, FACEP, FUHM, FACMT, Medical Toxicologist, Co-Medical Director, and Interim Executive Director of the National Capital Poison Center told Verywell Health.The Food & Drug Administration (FDA) does not regulate any period products, so there is no way to know if period underwear or other menstrual products contain PFAS or other chemicals. Why Trust Verywell Health Nicole Crawford is a long-time writer and editor, as well as a prenatal and postpartum birth doula, yoga instructor, and avid runner based in Maryland. She received her master’s degree in 2008 and specializes in women’s health, prenatal and postpartum fitness, and nutrition for busy families. 2 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. National Cancer Institute. PFAS exposure and risk of cancer. National Institute of Environmental Health Sciences. Perfluoroalkyl and polyfluoroalkyl substances (PFAS). See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit