A (pretty) definitive guide to period-proof underwear

The best period-proof undie brands for more sustainable periods

Whether your monthly is light or heavy, here we break taboos and guide you toward a more sustainable period. From a (very) personal experience, Gabi also writes a useful comparison of two of the most well-known brands of period-proof underwear: Modibodi vs Thinx.

There are a small handful of personal products I own that I can claim actually changed my life. I count four, to be exact. The other three make me sound vain, so today I’m going to focus on the most recent of my life-changing products (and the only one really relevant to a website focussed on sustainability). Period-proof underwear!

When I use the word ‘recent’, it’s relative. I discovered my life-changing acne cream when I was 17, so I can’t remember my adult life without it. But I’ve still had a solid two years to test these. That’s 24 periods. I actually just checked my email history and it turns out I almost bought three pairs back in June 2015 (‘Hey Gabi, looks like you’ve left something in your cart!’). Let me tell you- I would have had a seriously improved year had I bit the bullet.

So without further ado, your definitive guide to period-proof underwear…


First of all, Gabi, what the hay is period-proof underwear (more specifically than the best thing to happen to your life since Jesus)? It’s all in the name. Period-proof underwear are undies you wear during your period; they look like normal undies, they feel like normal undies, but they’re absorbent like a pad.

period-proof underwear modibodi vs thinx
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In my experience, very. This is my sole form of protection during my period. I don’t use a cup, tampon, or pad. Not ever. And I am never caught out because these are comfortable enough to wear daily, and so they’ve almost taken over as my only underwear (great if you get discharge* throughout the month and want to give up panty liners). Of course, there are different absorbencies available. As long as you’re aware of how heavy you are at certain times throughout your period, you’ll be safe. For me, I use a heavy absorbency for the first 48 hours, and then I can taper off until I’m just wearing a period-proof thong near the end.

*Isn’t discharge the WORST WORD? Ick.

Most brands will advertise that their underwear can act as back-up for a tampon or cup, and if you’re not super heavy, they work on their own. Just for reference, I have endometriosis, so I wouldn’t say I’m light. But if you can bleed completely through a pad in an hour, then I’d say that the security these would offer you as a back-up to your tampon or cup throughout your period would make these life-changing. They’d provide peace of mind. FYI- Modibodi actually has bundles with cups at the moment.


I have had friends give me horrified reactions when I tell them that these are all I use throughout my period. Please let me reassure you that they are definitely not grosser than any other period product. I think they’re significantly less ‘gross’ than tampons. Because they wick everything away, I promise you won’t walk around feeling like your underwear is damp, as long as you take care to choose the right level of protection. If you experience heavy clotting, that’s easy to quickly tidy up when you pop to the bathroom and you’ll feel fresh all over again. If you’re unusually heavy, then use a tampon/cup and concurrently wear these so that you never worry about leaks or stains! They’re antibacterial, so they shouldn’t smell. You do need to rinse them out before you throw them in the wash, but you’re an adult and I’m sure you’re used to the sight of your own blood by now. If you’re not quite into adulthood yet, I think these are doubly worth a shot, as you can put on a pair before school in the morning and forget about them until you come home. And you will forget about them because they feel like underwear.

period-proof underwear modibodi vs thinx
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Like I just said, I have endometriosis. No matter what, my periods aren’t going to be comfortable. But when you’re already in a lot of pain, anything that feels even slightly annoying becomes heightened. These eased my discomfort for two reasons;

  1. I sound like a broken record, but they feel like normal underwear- nope, they don’t feel like you’re wearing a nappy, they don’t crinkle or rub like pads can and if you’re like me, you can avoid sticking anything up your fanny.
  2. They need replacing less often than tampons or pads, so if you’re stuck in bed in pain (I know that’s not all of us) then you don’t have to make the nightmare shuffle to the bathroom as often.

I imagine these would also be more comfortable for a girl or young teen new to getting their period. Anything is more comfortable than a pad, and period-proof underwear are a lot less daunting than a cup or tampon. On top of that, girls and teens are often irregular, but you could avoid the mental discomfort that comes with the fear of being caught out by wearing these daily.

These would also increase the comfort levels of anyone with vaginismus or chronic pelvic pain who are unable to use a tampon or cup.


They are GREAT for the planet. Like I said, I’ve had mine for almost two years and they’re going strong. I imagine I’ll get about five years out of these, total. That is a lot of single-use period products that I’m not sending to landfill. Some brands/styles will make for more sustainable purchases than others, based on where in the world you live and what fabrics you choose.

period-proof underwear modibodi vs thinx
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It all depends on what you personally enjoy wearing, and what values are most important to you because as far as I’m aware, there is no perfect brand. I have two brands in my arsenal: Modibodi and Thinx.

Modibodi is Australia-based and Thinx is US-based. Here’s what I’ve been able to learn about both…

-In terms of the earth

In terms of caring for our planet, whichever brand is based closest to you is probably best. I’m based in Sydney, so there’s a much smaller carbon footprint for me if I buy from Modibodi. Modibodi also makes the majority of their underwear with organic bamboo & merino which are sustainable fabrics. Thinx uses Nylon/Spandex for most of their underwear, which is not so sustainable, but they do have a new organic cotton line. If you’re trying to minimise your single-use plastics, go for Modibodi. They send their products in a reusable drawstring bag, whereas Thinx individually plastic-wraps each pair of underwear you buy. On the plus side, Thinx does recycle all of their fabric scraps, and they have a goal to produce zero waste by 2025.

-In terms of animals

If you’re vegan, Thinx is your only option. Modibodi uses wool in the gusset of every pair of underwear for its antibacterial qualities, and they source from Merino Perform Wool. Unfortunately, I can’t find any information on whether Merino Perform Wool is selected from sheep that have not had to go through the barbaric mulesing practice, so I’m going to assume they don’t have strict ethical policies around this.

-In terms of people

Thinx has donated 5,712 pairs of period-proof underwear since 2017 to those who most need them; survivors of domestic violence, refugees, and the homeless. They also have an education program on topics including human rights, identity, and reproductive health for girls aged 10-13 years, and they’re looking to expand the program this year to include all genders.

Modibodi also has a giveback program titled ‘Give a Pair’, but you must specifically choose to donate to it. When you choose to purchase a ‘virtual’ pair of underwear (as opposed to a physical pair for yourself), they match your donation, meaning that for every $25 you donate to Give a Pair, $50 worth of underwear is given to homeless women and girls.

period-proof underwear modibodi vs thinx
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-In terms of personal comfort

Modibodi is softer, and I love them for the beginning of my period when I’m either stuck in bed, wearing loose clothing and at night time. I generally find the natural fibres they use a lot more breathable. That is certainly not to say that these aren’t suitable for every day- if you rarely wear very fitted clothes, they’d be brilliant. I reach for these a lot. Their gusset feels a little thicker and more padded than Thinx’ do, which you’ll notice the first time you put them on, but this doesn’t affect my comfort. I’m typing this from bed on the first day of my period, wearing my most heavily-padded Modibodis (sensual high-waist bikini), and I can’t feel the padding at all.

For daily wear, and near the tail end of my period, I prefer Thinx. I’m a little OCD with VPL, and Thinx has nailed making these invisible under clothes. If you’re a comfy-cotton-Bonds type of girl generally, then stick to Modibodi, or try Thinx’s organic cotton line. But if you, like me, like to look like you’re not really wearing underwear at all, Thinx is fab. I only have three styles from them; their regular thong (I’ve got six pairs of these), their cotton thong and their regular cheeky. All of these are lighter styles. They feel the closest to normal underwear out of my entire collection, because the gusset is not at all thick. However, I’ve been impressed with how well they hold up even on medium-flow days when I’ve needed to wear something quite fitted. I’ll quickly let you know that you should size up with the cotton thong- the elasticated band cuts in and gives me muffin-top, which the regular thong and cheeky cut never has.

Modibodi does have a line of seamless underwear, but in my experience, seamless does not translate to a lack of visibility under clothes. It doesn’t really make a difference whether or not something has seams- what makes the biggest difference is whether something cuts into your body or sits flat. All the models on their website look like they have slight muffin-tops in the seamless underwear, and if that’s how the models look, then what hope do the rest of us have? I’ll be transparent and say that I used to work in an underwear store and frequently found this was the problem with some seamless underwear, and I, therefore, haven’t tried the Modibodi version. If you have, and you loved them, let me know!

period-proof underwear modibodi vs thinx
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Not at all, but you do need to have a good washing routine. Because I like to be as eco-friendly as possible, I’ve always used an eco-friendly washing liquid on an eco-cycle of my washing machine. Apart from the obvious earth-benefits, I also like this routine because it’s gentle on my clothes, so they last longer. After a while, I started to notice that my period-proof underwear were smelling a bit musty. It turns out, the eco-friendly wool wash I was using was gentle, but a bit too gentle. The fabric-conditioning ingredients can build up in the layers of fabric and start to smell. It’s an easy fix. Get a Dishwashing liquid (it’ll strip out any build-up of conditioning ingredients) and squeeze a good squirt into your washing machine (wherever you usually put your washing liquid/powder). I use Organic Care. Then set your washing machine to a long/heavy duty cycle. I usually wait ‘til I have quite a big load to put in, so that it feels like less of a waste of water. Regardless of how much washing you’ve shoved in, it still works out much better for the planet to use period-proof underwear than to use a bit less water but constantly buy single-use period products. When your washing comes out, everything should smell fresh as a daisy!

Here are my final two tips for keeping your underwear in good condition!

  1. Line-dry underwear in the shade
  2. Wash your nude underwear with your whites. It won’t affect your whites at all, but your nude underwear will stay nude, rather than getting that gross greyish tint 😉

So what are you waiting for?! Go buy yourself/your daughter/your best friend a pair & then let me know what you thought!  

period-proof underwear modibodi vs thinx
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    4. Plastic-free periods: healthy flow & planet-friendly
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Gabi Goddard

Growing up with a fashion designer for a mum had its pitfalls; You had to watch for stray needles that found their way round the house and into places with heavy foot-traffic (or, you know, your pillow). But it had its upsides; by the age of ten developing the mundane superpower of spotting a silk cotton blend from ten metres away. It also grew a life-long love of creative sartorial expression in Gabi. Aside from that, she has an interest in arranging words into sentences which pushed her to study creative writing, which she’s currently doing at snail’s pace at UTS. Gabi cares deeply about protecting the Earth we’ve been entrusted with and treating every human on it with dignity. She combines her passion for all these things to bring you articles focussed on how you can be ethical and sustainable in your fashion choices without exclusively wearing undyed hemp made from your own marijuana plot.

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