Editor's note: We recently updated this piece to include Saalt menstrual wear. Lunapads also rebranded as Aisle, so we changed its labels and will be retesting when we can.
If you are a person who has a period, you probably already know that the perfect product for that time of the month doesn’t really exist—but that’s never stopped anyone from picking a favorite. There are the tampon fans, the menstrual cup enthusiasts, and the maxipad loyalists. But in the last few years, a new, trendy period product entered the collective menstrual consciousness: period panties.
Period panties are underwear with a built-in absorptive layer that you can wear during your period, either as a replacement or reinforcement for leak protection with other period products, depending on the panties’ claim of absorption. Thinx is likely the brand you’ve heard the most about—it’s gone viral a few times, most notably in regard to controversial subway ads in 2015 that stirred up a larger conversation about period stigma—though a bunch of other brands, like Dear Kates, Modibodi, and Knix are beginning to crop up in the space (and, if your internet presence is anything like mine, on your Instagram feed). After weeks of testing, our favorite period underwear is the Thinx Hiphugger(available at Thinx for $34.00).
These are the best period underwear we tested, in order:
Thinx Classic Hiphugger
Modibodi Sensual Hi-Waist Bikini
Dear Kate Ada Thong
Thinx Super Hiphugger
Dear Kate Brief
Modibodi Seamfree Bikini
Saalt Elemental Bikini
Lunapad / Aisle Boxer
Lunapad / Aisle Bikini
Knix Leakproof Bikini
Knix Leakproof Thong
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Modibodi Sensual Hi-Waist Bikini - Heavy Overnight Absorbency
Testers—myself included—agreed on one significant high point with the Thinx Classic Hiphugger: It looks and feels like a regular pair of underwear with a slightly thicker area along the crotch, where the absorptive gusset is. The Thinx also felt secure and true to size, which is important: When you’re wearing period underwear, you don’t want any slackness around the crotch, but you don't want it to feel too tight, either.
The pair claims to hold about two tampons’ worth of fluid, which checked out for me. I put them on right after I woke up during a moderate-to-heavy day of my period, then wore them through a work day and to a workout class—about 10 hours in total—and didn’t experience any leaks. Testers had similar results. The Thinx didn’t perform as well in lab tests as some other pairs of underwear—our test pair absorbed the moisture a little slower than some others. But for us, the positive user experience is enough to designate them our top choice.
“I’m obsessed with these,” one tester says. “Seriously, I was so skeptical, but now I'm a convert.”
The Thinx Classic Hiphugger comes in women’s sizes XS to 3XL.
Modibodi Sensual Hi-Waist Bikini - Heavy Overnight Absorbency
The Modibodi Sensual High-Waisted Brief scored the highest out of all the underwear we tested, earning perfect marks in water, blood meal (a kind of fertilizer made from animal blood that we used for testing), and towel-transfer tests. It also fared well—though not as well as tester favorite Thinx—in comfort and style. The external layer is made of bamboo and spandex, which provides a soft, stretchy feeling, and the inside is made of merino, spandex, and polyester, which provides absorption for heavy flow days without feeling scratchy. Testers said the Modibodi pair fit true to size, provided sufficient protection and, because of the style—a standard bikini with a subtle lace trim on the waist—look like something they’d pick out at a store whether they were period underwear or not.
The only caveat is the crotch area, which has noticeably thick padding—not quite as thick as a maxi pad, but thicker than a standard pair of underwear—that some people might find uncomfortable. Still, if you’re planning on wearing period underwear on heavy days or overnight, this Modibodi pair is your best bet.
Also, Modibodi ships out of Australia, so it can take a while to arrive—one order I placed took about two weeks, though another only took about a week.
The Modibodi Sensual High-Waist Bikini comes in women’s sizes XS to 6XL.
We tried out a few different thongs in our tests, and—perhaps unsurprisingly, given that most only promise to hold about one or even only half of a tampons’ worth of fluid—none of them held up that well in tests.
Still, the highest-performing thongs we tried out were the ones from Dear Kate, which claim to be equivalent to about one light tampon. (We tested the Ada thong in the lab and the Hazel and Ada thong in personal tests, because the Ada was out of stock in some sizes when we re-ordered.) Both look like normal thongs—the Ada has lace trim and the Hazel has a more streamlined, athletic look—and have a wider crotch area than other thongs we tested, which helps catch blood.
Some testers—and online reviewers—said they run small, so if you’re between sizes, it’s best to size up. On lighter days, or when you simply must wear a thong when you’re on your period, you want a thong from Dear Kate. One tester used the Dear Kate thong as a backup to a tampon when working out and said it gave her peace of mind and no visible panty line under her leggings.
The Dear Kate Ada Thong comes in women’s sizes XS to XL.
The Dear Kate Hazel Thong comes in women’s sizes XS to XL.
I’m Sara Hendricks, a staff writer at Reviewed. I have had about 140 periods in my life (give or take a few), and ever since Thinx’s first attention-grabbing ad campaign, I was intrigued, if skeptical, by the claim that a pair of underwear can work as a replacement period product. (Full disclosure: In my previous life as a freelance writer, I wrote a TMI-laden personal story about one of the worst UTI experiences a person can possibly have for Thinx’s blog.) With the help of Reviewed’s senior scientist Julia MacDougall, a few fellow period-having staff testers, and some blood meal, I put popular period underwear brands to the test to determine the best ones out there.
In order to see how each pair of period underwear reacted to a variety of liquids and wear conditions, we devised two different types of tests.
In the second test, we maintained the 15-gram total weight, but replaced 3 grams of water with 3 grams of blood meal, a powdered fertilizer that is partially made up of animal blood, creating a more viscous fluid. That may sound gross, but we wanted to be able to test the period underwear with a solution that looked and smelled like blood; this would help us to assess underwear leakage and cleanliness (as the metallic smell of the blood meal is a pungent one).
Once these liquids were prepared, we applied them to the underwear in two different configurations. In the first configuration, the underwear was suspended in mid-air. This setup helped us to get a sense of how quickly the underwear absorbs liquid, as well as how easy it would be for the liquids to soak through or leak along the sides of the panties.
In the second configuration, we laid the underwear flat onto a towel, applied the liquid, and then covered the underwear with a second towel, and weighed it down for an hour. This setup gave us a sense as to how any leakage would affect the clothes being worn on top of the period underwear.
Lastly, in between testing each liquid and each configuration, we washed the underwear according to wash instructions. After each wash, we assessed the cleanliness of each pair of underwear, which basically came down to whether or not we could still see or smell evidence of the bloodmeal.
Based on the lab testing, we narrowed down the list of period underwear to the top-performing brands—Modibodi, Thinx, Dear Kates, and Luna Pads—and asked four testers to try out a pair from each brand, allowing them to select their own color and style within that brand. They wore the underwear over the course of a month to test for style, comfort, and effectiveness. I also wore each pair of underwear, even the ones that didn’t make the first cut, during my period.
Who Should Use Period Underwear?
Before getting into this, I should make a general period underwear disclaimer: Period underwear works like a pad, in the sense that it collects menstrual fluid once it has left the body. Period panties tend to be slimmer and are less likely to shift out of place than pads, but if you’re typically a tampon or menstrual cup user, you will “feel” your period more with panties than you would with your internal collection method. Because of this, we recommend using period panties for a few things:
Wearing on days in the early and later stages of a period, e.g., when it could come or could be finished, but you aren’t totally sure and don’t want to wear a tampon
As a backup with a tampon or menstrual cup for peace of mind
For people who usually wear pads but want to replace them with something reusable
For people who might wear tampons or menstrual cups during the day, but like wearing pads at night
Other Period Underwear We Tested
Thinx Super Hiphugger
The Thinx Super Hiphugger claims to hold up to four tampons’ worth of blood—and, as far as I could tell, this is accurate. This pair scored third in our lab tests, right behind both Modibodi pairs. And when I wore this pair, I felt securely leak-free. It also looks nice, with a full-coverage bottom and lace trim around the waist.
The main drawback of this pair is that the outer shell is made of a slick fabric that looks and feels like a bathing suit. There isn’t anything wrong with this, but I didn’t love the way it felt when it rubbed against my clothes.
The pair also has extra thick padding in the crotch, even thicker than the Modibodi pair. Though this undoubtedly helps them maintain the four-tampon claim—and does a good job of absorbing liquid quickly and resisting sogginess—wearing it felt a little more diaper-y than I would have liked, just because the lining was so hefty. Still, leaking was never a concern when I wore the pair overnight, so it’s a great option for nights or heavier days.
The Thinx Super Hiphugger comes in women’s sizes XXS to 3XL.
The Dear Kates Nellie briefs, which claim to absorb up to two tampons’ worth of blood, placed fourth overall in our lab tests. They had the quickest absorption time of any we tested, soaking liquid up almost immediately in the crotch without dripping moisture through to the other side. They were easy to wash because the gusset is built into a wider area than most period panties, which means they have fewer seams (and fewer creases for menstrual fluid to get stuck in).
They also look pretty good, if not as stylish as the Thinx and Modibodi pairs—most testers were unimpressed, but not turned off by their aesthetics. “These were exactly fine in terms of looks,” one tester says. “They're not ugly, but they're more function than fashion.”
My main issue with them was the slippery material on the external shell of the underwear, which gave them a distinct look—and feel—from other pairs of underwear in my drawer, almost like wearing cheer briefs under my clothes. Also, this pair seemed true to size for me, but some testers complained theirs ran small, particularly around the legs.
Their absorption is great, though, so if that’s all you’re looking for, these briefs are worth a try.
Dear Kate Nellie Briefs come in women’s sizes XS to 3X.
Modibodi Seamfree Bikini - Moderate / Heavy Absorbency
The Modibodi seamfree bikini came in second place in our lab tests, right behind the high-waist bikini in our tests. This is significant, as the seamfree bikini is listed as having “moderate-heavy” absorption compared to the high-waist bikini’s “heavy-overnight” absorption.
The fabric it’s made of is nice—a silky elastane that feels close to a regular seamfree pair I have from ASOS—but because it’s thin (a byproduct of being seamfree), the padding in the crotch really stands out. It’s not prominent enough to see through clothes, but you definitely notice it when it’s on, and I felt a little weird putting it on at the gym. That said, I found it effective during my period—except for one thing. The crotch area, though absorbent, often crinkled up when I sat down. Because of this, I had to unfold it every time I went to the bathroom to prevent spillage. No leaks happened, so it wasn’t disastrous, but it wasn’t ideal.
The Modibodi Seamfree Bikini comes in women’s sizes 2XS to XL.
It’s common practice for period-havers to divide the underwear they own into at least two categories: Cute underwear, and underwear to wear when you’re on your period. Most absorbent period panties fall into the latter category—serviceable, but not exactly a pair you’d want to wear on an occasion when someone else could be seeing them. But the underwear from Saalt, a menstrual cup brand that recently branched into menstrual wear, is a rare exception. Saalt’s panties are made of a lightweight, silky material and have mesh or lace cutouts that make them look sleek and sophisticated. The absorbent gusset built into the crotch is also thinner than expected, so there’s almost no tell that it’s there at all, especially if you get a pair in a darker color. All in all, they’re comfortable, lightweight, and easy to forget you’re wearing period underwear.
On the downside: The pair we tested, the bikini, was advertised as having regular to high absorbency. But we found that it was not as absorbent as others in the same purported range and experienced a few leaks in lab tests, so it’s not a pair to wear alone on a moderate or heavy period day. I wore the pair on its own on a lighter day, which worked well, and expect it would work as a backup with a tampon or menstrual cup on heavier days—I wouldn’t expect to use these as a full-time free-bleeding solution, though. But if you want a pair of period underwear that doesn’t look like, well, period underwear, Saalt is your best bet.
The Lunapad brand is a little different than other period panty brands. Instead of selling a pair of underwear with absorptive material built into it, Lunapad sells reusable pads that can be inserted into different pairs of panties, including ones from its own line. If you buy a pair of Lunapad underwear, it comes with a pad and has two straps sewn into the underwear to keep the pad in place.
The pads themselves scored pretty high in leakage prevention, but didn’t do great in terms of absorption—instead of immediately soaking up liquid, it pooled on the surface of the pad for a while before eventually sinking in. I, uh, noticed this when I wore the Lunapads on my period. As soon as I put them on, they felt a little like a diaper, and I kept having to run to the bathroom to make sure I wasn’t leaking. I never was, but it wasn’t a great feeling. That said, for sleeping, I loved the boxer briefs, which claim to absorb about two tampons’ worth of fluid. They have a lot of coverage, are made of a soft, comfy cotton, and I wasn’t as aware of the damp feeling when I was asleep. I just found them way too bulky to wear during the day.
Because wearing these requires inserting a separate pad, it could be too much of a hassle for some people. Also, some testers complained that the pad got scrunched up when they moved—not surprising, considering the only thing holding it in is a strip of fabric—which could cause unexpected leaks. I didn’t experience this, but it’s still worth keeping in mind.
The Lunapads Boxer Brief comes in women’s sizes XS to XL.
The Lunapad Maia Bikini cut is similar to the boy short, only without the added leakage reinforcement of the shorts (and, therefore, slightly lower performance in our tests).
None of our testers were wild about the way they looked and felt. Because they’re made of cotton, they avoid the bathing suit look and feel some period panties have, but the bulkiness of the pad was generally unappealing. “They fit well when I first put them on, but they rubbed weirdly and became ‘cheeky’ when I walked around in them,” one reviewer says. “Not great.”
Still, most of the issues with Lunapads came from movement. Because of this, I feel OK saying that Lunapads are a pretty good option for sleeping, especially if you usually wear pads at night and want to cut down on waste.
The Lunapads Maia Bikini comes in women’s sizes XS to XL.
The Thinx thong is... fine. It only claims to hold about half a tampons’ worth of fluid, so I didn’t expect too much from it in regard to period protection, and it met my mediocre expectations. It scored in the bottom-middle of lab tests, with some leaking but a decent liquid absorption speed.
I found the thong comfortable and cute enough, but it was nothing special. One reviewer noted that the lace started to separate from the underwear on one side after a wash, so it may not be as durable as some other pairs of underwear. The thong should work for a light day or as backup with a tampon or menstrual cup, but you shouldn’t plan on using it for much more.
The Thinx thong comes in women’s sizes XXS to 3XL.
Sustain Natural, a company that makes organic pads, tampons, and condoms, also makes period underwear. The underwear comes in one style, a black cotton bikini, which the brand says holds the equivalent of one tampon.
My experience with them wasn’t memorable. In fact, I forgot I'd tested them when I was putting this article together until the very last moment. I liked that they are made of cotton and don’t require a supplementary pad, which made them feel more breathable than some other pairs. On the other hand, they look and feel like a frumpy pair of cotton undies.
I wore them on a light day, which went fine. (I don’t remember any leaks, anyway.) In short, the Sustain underwear does pretty much exactly what it claims, but they don’t reach as high as some other brands and are by no means the best of the bunch.
Sustain Natural Period Panties come in women’s sizes XS to XL.
Bambody period panties, sold on Amazon, have good ratings—129 reviews and an average of 4.3 stars—but we found them to be just OK. In tests, they took a while to absorb liquid and had some minor leakage. I found that they ran small, and noticed that the gusset doesn’t extend to the back of the underwear, which could cause leaks if the underwear shifts forward during the day.
On its Amazon page, the brand advises pairing with a tampon, pad, or menstrual cup for best results—so, if you get them, do that, I guess. As a plus, they’re less expensive than most other brands— $14.90 for a pair or $29.90 for a three-pack —so if you test them out, you don’t have to sink as much money into them as you would for a pair of Thinx.
The Knix Leakproof Bikini scored second-lowest of our lab tests, beating out only the thong of the same brand. That seemed to check out during my own test, too—I tried wearing it on its own, then, about an hour in, I realized I needed tampon reinforcement.
That said, the underwear is comfy enough, so it’s something I can see wearing on light spotting days or in tandem with a tampon—but definitely not solo when I’m in the throes of my period.
The Knix Leakproof Bikini comes in women’s sizes S to XXL.
The Knix thong does one thing really well: staying invisible under clothes. Other than that, it doesn’t offer much—it had the lowest score in our lab tests, due to noticeable leakage and just so-so absorption. Stains also seemed to stick to them more than other pairs.
Wearing the thong wasn’t the most rewarding experience, either. I found that it gave me too much of a wedgie feeling, even for a thong, and the padded area didn’t quite line up with the area that needed it, which, if I’d been wearing it on a heavy day of my period, wouldn’t have been ideal.
I might suggest wearing these on super light days, or maybe under leggings during a workout as tampon backup, but not for anything other than that.
The RubyLove Hipster didn’t fare terribly in lab tests, placing about fourth to last when compared to other brands. But in my practical test, it was a massive flop. The pair has a thick gusset, and RubyLove’s site claims the underwear provides “100 percent leak-proof protection,” so I thought they would be OK to wear on a medium-heavy day of my period. This was not the case! I wore the underwear out on a Saturday, and within two hours I had bled through it and onto my shorts, causing me to run into a Starbucks bathroom and create an emergency middle school-style toilet paper bundle.
The RubyLove pair also has a movable mesh layer on the crotch that can be used to hold reusable pads sold by the brand (though the pads aren’t supposed to be necessary for period protection). Not only does this feel weird if you don’t have one of the pads, but it also makes it so that anything that comes out during a period is really hard to wash out. I’m sure the underwear does work better with a pad and would be fine on its own on a light day, but I can’t recommend them based on my experience.
The RubyLove Hipster comes in women’s sizes XS to 3XL.
We use standardized and scientific testing methods to scrutinize every product and provide you with objectively accurate results. If you’ve found different results in your own research, email us and we’ll compare notes. If it looks substantial, we’ll gladly re-test a product to try and reproduce these results. After all, peer reviews are a critical part of any scientific process.