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9 best period underwear: Thinx, Knix, ModiBodi

We rounded up top-rated period underwear for every type of flow based on gynecologists’ advice.
Unlike disposable pads and tampons, period underwear is designed to be reusable and minimize single-use waste.
Unlike disposable pads and tampons, period underwear is designed to be reusable and minimize single-use waste. Knix; Saalt

While pads and tampons have reigned supreme since around the 1930s, alternative menstrual products — including period underwear, menstrual cups and discs — have gained significant traction in the past few decades. Interest can be attributed to several factors, including shoppers valuing sustainability, cost effectiveness and more willingness to talk about menstruation in general.

“As folks begin to talk more openly and more often about menstruation and menstrual health, they share options beyond what they assume to be the one and only method of care — typically commercial pads and tampons,” says Chris Bobel, professor of women’s, gender, and sexuality studies at the University of Massachusetts, Boston.

Period underwear is reusable, designed to handle the different flows throughout your period and helps those who menstruate move away from traditional disposable pads. And unlike “period panties” that keep pads in place during that time of the month, period underwear can act as either a worry-free backup to a tampon, cup or disc or take the place of tampons and pads altogether.

To better understand how period underwear works (and whether it’s safe to use), we spoke to gynecologists about its benefits, limitations and best uses. We also gathered some highly rated options to consider based on their guidance.

SKIP AHEAD Best light absorbency period underwear | Best moderate absorbency period underwear | Best high absorbency period underwear | How to shop for period underwear | More about the Thinx class-action settlement

Selected.Our top picks

What exactly is period underwear?

Period or menstrual underwear is specially designed to absorb menstrual blood, so you rarely need to use pads, tampons or cups in conjunction with it, according to Dr. Andrea Zuckerman, chief of pediatric and adolescent gynecology and vice chair of gynecology at Tufts Medical Center. It’s designed to look like normal underwear: You’ll see period underwear offered in all sorts of styles, including boyshorts, bikinis, briefs and thongs.

While period underwear may resemble any other standard pair, it has a built-in pad with a moisture-wicking top layer that draws away wetness and dries fast, plus a super absorbent core layer, says Dr. Carolyn Moyers, a board-certified OB/GYN and founder of Sky Women’s Health.?

A lot of period underwear is made from cotton and absorbent microfiber polyester, with some nylon or elastane thrown in for stretch and durability, according to our experts. Best of all, you usually can’t even tell there’s a pad built in — there’s little bulging and you don’t have to deal with the annoying issues that come with traditional pads, such as adhesive and wings.

How we picked the best period underwear

Below, we highlight the top factors our experts recommend keeping in mind when shopping for period underwear.

  • Absorbency level: There are three main absorbency levels for period underwear: light, moderate and high. Most period brands determine the absorbance level by how it compares to regular tampons, which our experts say typically hold up to five milliliters of blood each (though this varies by brand). Some of the most absorbent period underwear on the market can hold more than five regular tampons’ worth of blood, says Dr. Carolyn Moyers, a board-certified OB/GYN and founder of Sky Women’s Health. Based on our experts’ guidance, we consider light absorbency to be similar to one to two tampons, medium absorbency to be similar to three to four tampons and high absorbency to be equal to five or more tampons.
  • Material: Look for moisture-wicking fabrics like nylon and polyester, which absorb wetness and dry quickly.
  • Maintenance: Consider period underwear that’s machine-washable, which makes it easier to clean and reuse.
  • Fit: Period underwear comes in a variety of styles that mimic your typical underwear you would wear everyday, including full-coverage, cheeky, thongs and boxers. Consider the style that fits best for you and your lifestyle.
  • Ratings: We compiled period underwear with a 4-star average rating or higher across hundreds of reviews on the brand’s website or at major retailers.

Top-rated period underwear to consider

We separated the following pairs of highly rated period underwear into three categories according to absorbency level, per our experts’ guidance: light, moderate and heavy coverage. Each of the following period brands indicates its underwear’s absorbency level (either based on number of regular tampons, volume in milliliters, or both) and all underwear options are machine-washable.

Light absorbency period underwear

ModiBodi Sensual Hi-Waist Bikini

ModiBodi sells underwear for a variety of needs, including everyday, pregnancy and moisture-wicking. The brand’s period underwear is among its most popular pairs, and the Sensual Hi-Waist Bikini has earned an 4.9-star average rating from more than 3,100 reviews on its site. This bikini-style underwear is meant for lighter flows — about the same absorbency as two tampons — and is designed to sit right at the hip with a higher leg. The brand also offers a moderate-heavy pair that’s similar to two to three tampons, a heavy-overnight option that’s similar to three to four tampons, and a maxi version, which absorbs the same amount of blood as 10 tampons, according to ModiBodi.?

The underwear has a high-waisted fit and a lace trim, and it comes in seven colors and patterns. The bikini-style underwear is also made with a stain-, odor- and bacteria-fighting lining, according to the brand. It’s available in five colors, including beige, moss green and black, and in 10 sizes ranging from XS to 6XL.

Absorbency: 1-2 tampons (10 mL) | Sizes: XS to 3XL

Proof Leakproof Thong

Like Modibodi, period label Proof designs underwear for different needs, including postpartum, workout and maternity. The Leakproof Thong has the absorbency of about one tampon and is designed to both help with light leaks and erase panty lines, according to the brand. Made from a breathable microfiber fabric and with a low-rise silhouette, the underwear is primarily meant for spotting, sweat and other discharge, so it’s best to use it in conjunction with a tampon, according to Proof. It has a 4.9-star average rating from over 70 reviews at the brand’s site and it’s available in two shades: black and sand.

Absorbency: 1 tampon (10 mL) | Sizes: XS to 3XL

Thinx Cheeky

Thinx is one of the more well-known period underwear brands with lines designed for different ages and lifestyles, including one for tweens and teens called Thinx (BTWN) and another for bladder leaks called Speax. (Thinx settled a class-action lawsuit in 2022 claiming the brand’s underwear contains harmful chemicals. Thinx denies these claims and admits no guilt or wrongdoing. We go more in-depth about this below.)

Made from flexible nylon and elastane, this cheeky-style underwear, as well as the brand’s thong, has Thinx’s lightest absorbency level: up to one tampon’s worth of blood, according to the brand. Thinx also offers styles in four additional absorbency levels, including light (two tampons), moderate (three tampons), heavy (four tampons) and super (five tampons). The Thinx Cheeky has a 4.8-star average rating from over 1,000 reviews at Thinx.

Absorbency: 1 tampon | Sizes: XS to 4X

Moderate absorbency period underwear

Saalt Leakproof Mesh Bikini

Saalt, one of our favorite women-owned brands, is best known for its popular menstrual cups. But the brand also has a period underwear line called Saalt Wear, which includes bikinis, thongs and briefs aimed at absorbing periods, bladder leaks and more. The Leakproof Mesh Bikini, which has a 4.5-star average rating from over 300 reviews at Saalt, is designed to absorb as much as three regular tampons’ worth of blood, according to the brand. This pair is made from sheer mesh and offers a stretchy, mid-rise waistband.

Absorbency: 3 tampons | Sizes: XS to XXL

Aisle Boost Boxer

The Boost Boxer is designed with a statement waistband and an absorbency that matches up to four tampons, according to Aisle. The underwear comes with a booster that you can tuck into the ends of the gusset worth an additional four tampons of protection (or a total absorbency of about eight tampons), according to the brand. The underwear has over a 4-star average rating from more than 600 reviews at Aisle and comes in four colors: black, beet, ginger spice and kelp forest. In addition to period underwear, Aisle also offers its own line of liners, pads and cups.

Absorbency: 4 tampons (8 tampons with booster) | Sizes: XXS to 5X

Cora Period Underwear

Eco-friendly tampon and pad company Cora, which makes some of our favorite menstrual cups, also makes period underwear that absorbs the same as three regular tampons, according to the brand. The underwear — which has a 4.2-star average rating from over 1,000 reviews on Amazon — is designed to be flexible, especially for those with active lifestyles: It has a moisture-wicking core and elastane to make it stretchy and comfortable. It’s available in packs of one or three.

Absorbency: 3 tampons | Sizes: S to XXL?

Rael Bikini Reusable Period Underwear

Rael offers three underwear styles, each with different absorbency levels: a bikini style that can absorb as much as three tampons’ worth of blood, and high-waisted and boyshort styles that both offer up to five tampons-worth of protection, according to the brand. Meant to look and feel like everyday underwear, it’s made with four layers, including one from breathable cotton and another that’s meant to protect against moisture and odors, according to Rael. The brand recommends changing it after 5-8 hours of use.

In addition to period underwear, including a disposable pair for heavy flows and postpartum, Rael carries its own collection of menstrual cups, pads, tampons and panty liners. Like the other options on this list, Rael’s period underwear is highly rated, with a 4.5-star average rating from 40 reviews at the brand’s site.

Absorbency: 3 tampons | Sizes: S to XXL?

High absorbency period underwear

Knix Super Leakproof High Rise

碍苍颈虫’蝉 period underwear has multiple absorbency levels, ranging from light coverage (which absorbs the same as 1-3 tampons) and ultra, which absorbs the same as 5-8 super tampons. The Super Leakproof High Rise is among its most popular offerings: It has an average 4.6-star rating over more than 4,100 reviews on the brand’s site. The pair comes with an extended gusset that’s 9 inches long and four-way stretch that’s meant to create a more comfortable fit the more you wash and wear it, according to Knix. In terms of fit, this underwear sits at the natural waist. You can choose between 11 colors, including rose water (pink), orchid (light purple) and midnight (blue).

Absorbency: 8 tampons (40 mL) | Sizes: XS to XXXXL

The Period Company The High Waisted

As its name implies, The Period Company is centered around period underwear (the brand also offers reusable pads and panty liners that are more recent additions). Made with organic cotton and spandex, this high-waisted pair can hold up to 10 tampons’ worth of blood and lasts an average of 8 hours for a heavy flow, according to the brand. Along with The High Waisted, which earned a 4.2-star average rating from over 1,800 reviews on the brand’s site, you’ll also find The Bikini with a lower rise, The Boxer and The Adaptive Bikini, which has velcro closures.?

Absorbency: 10 tampons (148 mL) | Sizes: XS to 6XL

How to shop for period underwear

Period underwear is usually offered in three absorption levels for light, moderate or heavy flows. Menstrual underwear can hold as much as (and sometimes more than) five regular tampons’ worth of blood for heavier or overnight menstruation, which is more than most pads can hold, says Moyers. Light absorbency styles can hold about as much as a typical pantyliner.

Just like with pads or tampons, you should pick period underwear based on your specific flow. Our experts recommend trying out different absorbances to get comfortable wearing them and to see how each feels with your body and flow. If you have a heavier flow, you may want to use it in combination with other period products like a tampon or menstrual cup for extra protection and to avoid leaks, says Dr. Taraneh Shirazien, a board-certified gynecologist at NYU Langone and director of the Center for Fibroid Care.


More about the Thinx class-action settlement

A complaint filed in May 2022 alleged that Thinx had deceptively marketed its products as a “safe, healthy and sustainable choice for women that “is free of harmful chemicals,” when the presence of chemicals like PFAS and nanoparticles in some samples of the brand’s underwear “are a safety hazard to the female body and the environment.”

Thinx denies all allegations — emphasizing that the settlement was not an admission of guilt.

“Consumer health and product safety are top priorities for Thinx, and we stand by the quality, efficacy and safety of our products,” Thinx said in a statement to NBC Select. “PFAS is not included in our product design and we continue to take measures to help ensure these substances are not added to our products.”

As part of the settlement, Thinx agreed to reimburse up to $5 million to customers who purchased its underwear between Nov. 12, 2016 and Nov. 28, 2022.

Meet our experts

At NBC Select, we work with experts who have specialized knowledge and authority based on relevant training and/or experience. We also take steps to ensure that all expert advice and recommendations are made independently and with no undisclosed financial conflicts of interest.

  • Chris Bobel is a professor of women’s, gender, and sexuality studies at the University of Massachusetts, Boston.
  • Dr. Andrea Zuckerman is the chief of pediatric and adolescent gynecology and vice chair of gynecology at Tufts Medical Center. She is also an associate professor at Tufts University School of Medicine.
  • Dr. Carolyn Moyers is a board-certified OB/GYN and founder of Sky Women’s Health.
  • Dr. Taraneh Shirazien is a board-certified gynecologist at NYU Langone and director of the Center for Fibroid Care. She is also the director of the Division of Global Women’s Health at NYU Langone Health.
  • Dr. Tina O’Shea is a board-certified OB/GYN and an assistant professor in the department of obstetrics and gynecology at the University of Florida College of Medicine.
  • Dr. Lauren Naliboff is a board-certified OB/GYN and assistant professor in the department of obstetrics, gynecology and reproductive health at Rutgers New Jersey Medical School.

Why trust NBC Select?

Mili Godio is an editor at NBC Select who has covered a variety of wellness topics, including menstrual cups, face sunscreens and rosacea treatments. For this article, Godio spoke to six gynecologists and women’s health experts about how to shop for period underwear, the benefits and drawbacks of these menstrual care products and whether they’re safe to use. She also compiled highly rated options based on experts’ advice. ?

UPDATE (Feb. 2, 2023, 3:26 p.m. ET): This article was updated to include details about a now-settled class action lawsuit alleging Thinx — one brand we recommend — inaccurately marketed its products as free of harmful chemicals, notably PFAS.


Catch up on Select’s in-depth coverage of personal finance, tech and tools, wellness and more, and follow us on Facebook, Instagram, Twitter and TikTok to stay up to date.

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