Leakproof Thong
Rated 4.9 out of 5
Based on 75 reviews

Leakproof Thong

$25 Sale price
The G.O.A.T of Thongs
HSA/FSA Approved

AbsorbencyHolds up to 1 Regular Tampon or 2 Teaspoons


If you're tired of those pesky panty lines ruining your outfit, or scared of any accidental leaks, then our Proof® Thong is the superhero you need in your life! These undies are like your trusty sidekick, always there to save the day. Plus, they're so comfy, you'll forget you're even wearing them. And don't worry about dealing with period mishaps or sweat stains, our thong has got your back (or rather, your behind) covered. So, whether you're hitting the gym or just Netflix and chilling, our washable Proof® Thong is the perfect partner in crime!
Regular Lining

The Thong features an invisible leakproof core in the gusset. You’ll be comfortable and protected with our soft and slim multi-layer core.

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light periods


replace a panty liner

replace or back up a tampon



odor fighting

Outer: 75% Nylon 25% Spandex 

Lining: 100% Polyester 

Lining: 69% Cotton 25% Polyester 6% Acrylate. Imported.

Caring for your pair is easy. Simply machine wash cold on a gentle cycle. Do not bleach. Lay flat to dry. Do not iron. Do not dry clean.

Regular Lining

The Thong features an invisible leakproof core in the gusset. You’ll be comfortable and protected with our soft and slim multi-layer core.


The Thong is equipped with Leak-Loc® technology and light absorbency that holds up to 1 regular tampon or 2 tsp. That makes it perfect for light bladder leaks or periods, spotting, discharge, or sweat. The unique moisture-wicking lining and technical fibers wick moisture away from the body and inhibits the growth of bacteria while fighting odor.

Our leakproof, period-proof thong was designed with comfort in mind. Created with buttery-soft, stretch fabric that moves with the body and a thin, flexible gusset keeps you comfortable, day or night.

We typically advise buying your normal underwear size for the thong. For a more generous, high-rise fit, you may like a size up. For more size guidance, check out our size guide.

Oh yes! The Thong is great for everyday wear, as it provides light ‘back up’ protection for all of those in-between days. Smooth, seamless edges vanish under clothing to provide a sleek look under clothing.

The leakproof thong undie was designed with light periods in mind. If you have a low flow, the thong will pull moisture away from the body and into the Leak-Loc® core which holds up to 1 regular tampon or 2 tsp.

Sleep tight, all night long in the Proof period thong. Really, there are no rules regarding what you can and can’t do in this thong. With this breathable and buttery thong featuring leakproof protection you are ready for anything, day or night. Keep in mind though, the Proof period thong has light absorbency which means it holds up to 1 regular tampon or 2 teaspoons of liquid. If you think you’ll need more protection than this, Proof has plenty of other leakproof undies and thongs that offer more absorbency. The Proof period thong is best for sweat, discharge, spotting, light period leaks, and panty liner replacement.

The leakproof thong is available in black or sand. These color thongs are a staple to every women’s wardrobe - order both. You won’t regret it.

Yes and yes! Proof really has you covered - if you let them of course. Our leakproof undies are designed with several layers of moisture-wicking, absorbent materials that pull moisture away from the body and into a super absorbent core. They are designed to wick away sweat and moisture whether you're enduring an intense workout and taking an afternoon stroll. All the while, our proprietary technical fibers will be fighting odors too. See what we mean when we say we have you covered?

Proof’s leakproof thong can be worn every day, period or not. Our leakproof thongs can certainly prevent leaks during your period, but it’s designed to do much more. The leakproof thong is great for absorbing sweat, discharge, sweat, or spotting, as well as light period leaks.

All of Proof’s leakproof thongs and undies can be worn while working out. In fact, we recommend doing so. Whether you’re on your period or not, the leakproof thong can offer several benefits while working out. It can help absorb sweat while fighting odor, keeping you cool, dry, and focused on your workout.

No need. In fact, you can make a big environmental impact by not wearing pads or tampons. Proof leakproof undies are designed to be a reusable alternative to single-use plastics. By eliminating the use of pads and tampons, you can impact the overall well-being of our planet. Tampons, pads, and panty liners are a huge source of waste. On average a single woman disposes of about 11,000 tampons in her lifetime. Each year an estimated 20 billon pads and tampons are thrown into North American landfills. With a lack of oxygen, it’s unlikely that these products will decompose. It could take 800 years for non-recyclable female care products to actually decompose. By wearing Proof leakproof undies you can make a big impact.

Imagine breathable, buttery soft fabric that makes you feel free. We’ve all (hopefully) had that ahh moment slipping on a dreamy pair of underwear. Now imagine if you could have that same feeling while knowing you can stay dry and confident all day or all night long. It’s empowering. Slip on the leakproof thong and worry about what’s important in life, not your underwear. Besides, it’s so comfortable you’ll probably forget you are even wearing any. The real proof though, is in our reviews