Best Underwear for Periods, Including Sustainable Options

If you've ever ruined a favourite pair of underwear mid-cycle, you already understand the appeal of period underwear. But period panties have come a long way from a backup-plan product. They're now a genuinely comfortable, leak-resistant, and often far more sustainable alternative to disposable period care.

Below, we break down exactly what period underwear is, how it works, why so many people are making the switch, and which sustainable options are worth your money.

What Makes the Best Period Underwear

The absorbent core is the foundation. Bamboo and organic cotton pull moisture away from the skin quickly, hold more fluid, and are far kinder to sensitive skin than synthetic blends. A well-constructed core also stays slim, as multiple absorbent layers don't have to mean bulk. If it feels like a pad between your legs, the design hasn't done its job.

Leakproof technology lives in the outer layer and needs to genuinely seal, particularly at the gusset edges where most leaks actually happen. The best options hold up across hours of real movement without sacrificing breathability.

Fit affects protection as much as absorbency does. A pair that gaps or rolls will leak regardless of how well it's made. Look for a true size range that includes XS through XL at minimum.

When buying period underwear, you need to think of your whole cycle. You want tight styles for spotting or the tail end of your period, medium for average days, heavy or overnight options for peak flow. Period underwear works best when the absorbency level actually matches what your body needs that day.

Sustainable Period Panties Brands to Consider

Nookees Period Underwear: Designed for Comfort, Flow, & Everyday Wear

NOOKEES Free Bleeding Organic Cotton Period Panties

Nookees was invented by German journalist and entrepreneur Janina Breitling, and it's genuinely different from anything else on the market. The core idea is a patent-pending click-in system, where instead of a built-in absorbent gusset like conventional period underwear, Nookees is made from two components which includes THE PAD and THE PANTY. You click the reusable pads into the panty using three snap buttons, and when it's time to change, you unclick the pad, rinse it, and snap in a fresh one without taking your underwear off. That's a practical difference most period underwear can't offer.

The materials

THE PANTY is made from lyocel, which is a sustainable fibre derived from cellulose, a natural component of wood. It's biodegradable, and at the end of its life cycle the fibres can re-enter the ecosystem. This means there is no polyester and no petroleum-based synthetics sitting against your skin all day.

THE PADS are made from 100% organic cotton, IVN Best certified, and available in four absorbency levels that include light, medium, heavy, and a "Splash" edition for those who want an added backup layer. The organic cotton is naturally breathable, pesticide-free, pigment-free, bleach-free, and hypoallergenic, making it ideal for the sensitive vulvar area.

No PFAS, no plastic, no biocides

This is where Nookees pulls ahead of most of the competition. Conventional period underwear is often made from polyester, full of plastic, and contains chemicals like PFAS and biocides such as nano silver or silver chloride, and can only be washed at low temperatures. Nookees contains none of these. It is completely free from toxins, biocides, and synthetic materials, including in the absorbent pads themselves, which is where most brands quietly cut corners. Even the nickel-free snap buttons have been tested against a list of up to 350 toxic chemicals and carry OEKO-Tex 100 certification.

The light pad uses a 3-core layer technology for slow flow days. The medium uses 4-core layers for average days. The heavy uses 5-core layers for peak flow or overnight wear. nookees The starter kit, called THE KIT, comes with one pair of panties and all three pad weights.

Because Nookees uses organic cotton with a specific weave, the pads can be washed at up to 60°C. Most period underwear is limited to 30–40°C washes, which isn't hot enough to reliably eliminate bacteria.

Sizing and fit

THE PANTY comes in sizes XS through XXL, sized by hip measurement: XS (89–94cm), S (95–97cm), M (98–104cm), L (105–108cm), XL (109–118cm), XXL (119–124cm). The lyocell fabric has a comfortable stretch to it, and if you're between sizes, Nookees recommends going smaller rather than larger for a better fit and seal.

Through the Nookees Foundation, the brand has donated over 40,000 reusable period pads through projects in Uganda, South Africa, and Nepal, partnered with organisations including the Toni Garrn Foundation and Girls on a Mission. Every purchase contributes to that.

Thinx

Thinx is probably the most recognisable name in period underwear, as this is the brand that put the category on the map with bold subway ads and a product that, at the time, felt genuinely new. They've been around since 2013, and their range has grown considerably since then.

Thinx has five styles of period underwear to choose from: hiphugger, brief, hi-waist, shorts, and bikini NBC News, plus sleep and teen ranges.

Their newest styles feature all-day absorbency for up to 12 hours of period protection, holding up to 12 regular tampons' worth of flow, which is among the highest capacity on the market. The LeakSafe barrier is their built-in leakproof technology, and the super absorbent core layer is designed to handle up to three regular pads' worth of flow across a full day.

Thinx is available in sizes XS through 4X, which is one of the broader size ranges available. This is and a genuine plus for a category that has historically been pretty limited in inclusive sizing.

The PFAS history

In 2020, independent testing found fluorine levels of 3,264 parts per million in the crotch of Thinx organic briefs, which is high enough to suggest PFAS was intentionally added. Following the article's publication, several lawsuits were filed against Thinx, which were eventually merged into one class-action case. In January 2023, Thinx settled for up to $5 million. The company denied all allegations and admitted no wrongdoing, but committed to taking steps to ensure PFAS are not intentionally added at any stage of production, and to adjusting some of its marketing language.

Thinx now states that their products arePFAS-free and carry OEKO-TEX 100 Class II certification, with finished products tested through accredited third-party labs. That's a meaningful shift in their testing and transparency standards.

The sustainability question

Thinx markets itself as a sustainable alternative to disposables, and in terms of reducing single-use waste, that's true. But it's worth noting that their synthetic fabrics are made from virgin plastic, not recycled materials, and the only Thinx style made with organic cotton was recently discontinued.

ModiBodi Leakproof Underwear

Modibodi is an Australian brand that's been around since 2013 and has built a solid reputation as one of the more serious players in the period underwear space, particularly when it comes to range, absorbency, and sustainability credentials. They were among the first period underwear brands to show actual menstrual blood in their advertising, which at the time was quietly revolutionary, and their product line has only grown since.

Modibodi's protection comes from a patented three-layer lining that wicks away moisture, absorbs blood, and minimises odour. It is built slim enough that it looks and feels like regular underwear from the outside. The top layer is merino wool, which naturally absorbs fluids and controls odour. Below that, a quick-drying microfibre middle layer absorbs and locks fluid away, while the bottom layer provides the waterproof seal. Products are lab-tested to maintain their leakproof function for up to 100 washes.

Absorbency range

Modibodi covers the full spectrum. Super light holds around 5ml, which is roughly one tampon for discharge or spotting. Light to moderate holds 10ml, equivalent to two tampons, for lighter period days or bladder leaks. Moderate to heavy holds 15ml, around two to three tampons, for medium to heavy days. Their Maxi styles go higher, holding up to 10 tampons' worth of fluid, which makes them one of the better overnight options in the market.

Styles and sizing

Styles range from briefs and bikinis to Brazilian cuts, thongs, and boyshorts, as well as active leggings, swimwear, and a teen range. Sizing runs from XS to 6XL, which is one of the most inclusive ranges available in period underwear.

Materials and the sustainability picture

This is where it gets nuanced. The outer fabric across most of Modibodi's range uses bamboo viscose, merino wool, TENCEL, or GOTS-certified organic cotton depending on the style, which are all reasonably clean choices. All products carry OEKO-TEX Standard 100 certification, tested as free from harmful substances including allergens and carcinogens. They're also PFAS-free and ZDHC compliant.

But the absorbent gusset is where the material story gets more complicated. In their standard range, the absorbent layer is 100% polyester and the leak-resistant layer is 100% polyester PUL. That's plastic sitting directly against your skin, cycle after cycle. It's OEKO-TEX certified and PFAS-free, which means it's been tested for harmful chemicals, but it's still synthetic, and it does shed microplastics when washed.

Modibodi has addressed this directly with their biodegradable line. After two years of R&D, they launched what they describe as the world's first biodegradable period and pee-proof underwear, using a combination of TENCEL, merino wool, bamboo terry, and a biodegradable TPU film as the waterproof layer. According to the brand, 97% of the blend's components are scientifically proven to break down into nontoxic substances at end of life, with most materials decomposing within six months when buried in active soil. That's a meaningful step, though it applies to their biodegradable range specifically, not the full product line.

Knix

Knix is a Canadian brand that launched in 2013 and has built a loyal following, particularly for their Dream Short, which has near-cult status among people with heavy overnight flow. Their range is broad, their sizing is inclusive, and their marketing is sharp. But like Thinx, the brand's PFAS history is part of the story.

Knix organises their period underwear by absorbency level, which includes Essential, Light, Moderate, Heavy, and Ultra, with absorbency ranging from around one teaspoon of liquid up to seventeen teaspoons, depending on the style. That upper end is among the highest available, and it's what makes their heavy-flow options genuinely useful rather than just aspirational.

Styles run from thongs all the way to boxers, including high-rise cuts, bikinis, and their popular Dream Short, a boxer-style option with an extended front-to-back liner designed specifically for overnight protection. Sizes go from XS to 4XL, with a teen line called KT by Knix for younger people navigating their first cycles.

The gusset construction varies by style. Their Dream Short, for example, uses a four-layer system: a modal top layer to wick moisture, a SUPIMA cotton middle layer to absorb fluid, a polyester layer to lock it in, and a polybutylene terephthalate backing as the final leakproof barrier. But like most conventional period underwear, the inner layers that do the actual work are synthetic.

The PFAS history

This is where it gets uncomfortable. Knix built part of their brand identity on positioning themselves as a cleaner alternative, including taking aim at Thinx during the PFAS controversy in 2020. Independent testing then found 373 parts per million of fluorine in the Knix High Rise underwear, some of the highest levels detected across the brands tested in that study.

A class action lawsuit followed, and Knix settled for $1.4 million. As part of the settlement, the company agreed to remove all references to their products being PFAS-free, toxic chemical-free, or fluorine-free from their website, and to increase PFAS testing frequency for two years. Knix denied wrongdoing throughout.

Knix's current position is that they have never intentionally added PFAS to their products, and that they now partner with an industry-leading lab to test for organic fluorine, the form of fluorine that actually indicates the presence of PFAS, rather than total fluorine, which can pick up naturally occurring inorganic fluoride from ingredients like seaweed. The distinction is real and worth understanding, though the settlement terms speak for themselves.

Period Aisle

Aisle has been around longer than almost anyone else in this space. Originally known as Lunapads, the brand pioneered reusable period products back in 1993, long before period underwear became a mainstream conversation. They're a certified B Corp, women-owned and operated, and have spent over three decades refining what reusable period care actually looks like in practice.

Aisle's standout feature is their adjustable absorbency system. Their BOOST underwear includes a removable Booster, which is a pad-shaped insert that slides into slits at the front and back of the gusset, holding four tampons' worth of fluid on its own, and eight with the Booster in place. The idea is that you can swap the Booster out during the day without changing your underwear entirely, which solves one of the real-world frustrations of conventional period pants on heavy days.

Their range covers three absorbency levels: Light, for light to moderate flow; Super, for heavy days and overnight; and BOOST, their adjustable option. Styles include briefs, hipsters, bikinis, and boxer briefs, with sizing from XXS to 5XL.

Materials

The body of Aisle underwear is a blend of TENCEL lyocell, organic cotton, and spandex. The on-body gusset, which is the layer that actually touches skin, is 95% organic cotton and 5% elastane. The organic cotton gusset sits against skin, while the synthetic leakproof lining is positioned below it, not in direct contact with the body.

Aisle uses stitched construction rather than bonded or glued seams, which they say improves durability, reduces stiffness, and holds up better across 100+ wash and dry cycles. This a genuine quality-of-longevity consideration that most brands don't address directly.

Aisle conducts additional third-party PFAS testing beyond their OEKO-TEX certified materials, and no detectable levels of PFAS have been found in their underwear based on a detectable limit of one part per million. They're one of the few brands that have been independently blind-tested and cleared, which matters, given how many brands simply claim PFAS-free status without publishing results.

Social impact

Aisle gives back 1% of sales to individuals and nonprofits addressing period poverty and gender inequality. Their pads are made in Vancouver, Canada, and their underwear is manufactured in Phnom Penh, Cambodia, in women-owned and operated factories where all workers are paid a living wage.

The honest caveats

The BOOST system is clever, but it's not seamless. Several reviewers note that the Booster can shift or feel fiddly to swap mid-day, and that when it's in, the underwear adds noticeable bulk. The underwear can also roll slightly at the sides during heavy use. For people with lighter flows, the Essential range without a Booster gets consistently strong reviews for comfort and discretion.

Comparing Period Underwear

How to Wash and Care for Period Underwear

Most period underwear is specifically designed to last, but only if you treat it right. The absorbent materials and leakproof layers that give you reliable protection through your menstrual cycle are also the first things to break down if you wash them the wrong way. A few simple steps make the difference between a perfect pair that lasts years and one that loses its edge after a handful of cycles.

1. Rinse first, always

As soon as you take them off, rinse your period underwear in cold water. Warm water sets menstrual fluid into the fabric, making it harder to remove and harder on the multiple layers doing the absorption work. Rinse until the water runs mostly clear before putting them in the wash with your other garments.

2. Wash with fragrance-free detergent

Fragranced detergents and fabric softeners are the two things most likely to quietly destroy the leakproof technology in your underwear. Softeners coat the absorbent materials and reduce how much they can hold, which means less protection right when you need it most, whether that's a heavy flow day or overnight. Stick to a gentle, fragrance-free detergent and your leakproof underwear will stay soft, functional, and genuinely absorbent wash after wash.

3. Skip the heat

High heat from the dryer or a hot wash cycle degrades the leakproof lining over time. Most period underwear is designed to be washed cold and air dried. Hang them up after washing, let them dry fully before storing, and you'll preserve both the feel and the function. The exception is Nookees, which can be washed at up to 60°C thanks to their organic cotton construction, which is one of the few period underwear options that can handle a genuinely hygienic hot wash.

How Many Pairs of Period Underwear Do You Need

The Nookees Panty

The average menstrual cycle runs five to seven days. If you're using period underwear as your first line of protection and washing every two to three days, six to eight pairs is a comfortable rotation for most people. That gives you enough to cover your heaviest days without scrambling to wash and dry between wears.

If you're happy to rinse and hang dry daily, you can manage with as few as three or four pairs, but it does require consistency, and on heavy flow days you may find yourself going through two pairs in a single day.

Light vs heavy cycles

For lighter cycles, fewer pairs go further. Two to three pairs at a moderate absorbency level can cover the full menstrual flow comfortably, with enough buffer to wash between wears without feeling rushed.

For heavier cycles, you'll want more and you'll want the right absorbency levels in the mix. A couple of high-absorbency pairs for the first half of your cycle, a few medium pairs for the middle days, and one or two lighter options for the tail end gives you secure coverage without feeling bulky throughout.

Combining with tampons or menstrual cups

Many people prefer to use period underwear as added protection alongside a tampon or menstrual cup rather than as a standalone product, particularly on heavy days when leak protection matters most. In this case, you need fewer pairs overall, since each one is handling overflow rather than your full menstrual flow. Two to four pairs is usually enough for a full cycle used this way, which also makes the initial investment significantly more manageable.

This combination approach also lets you start small. Buy two or three pairs to begin, wear them as backup with whatever you're already using, and build your collection from there once you know which styles and absorbency levels work for your body.

The long-term cost case

Period underwear costs more upfront than a box of tampons. But at regular price, a quality pair lasts two to five years with proper care. Across that time, the average person spends significantly less on period underwear than on disposable products, even accounting for the higher starting cost.

It also adds up in less obvious ways. There will be no last-minute pharmacy runs. No polyfluoroalkyl substances against your skin month after month. No plastic waste accumulating from products used for a few hours and thrown away. The switch to super soft, reusable period underwear isn't just a financial decision, it's a different relationship with your cycle altogether, one that puts reliable protection and your clothes first, without the hidden costs piling up quietly behind the scenes.

Frequently Asked Questions