FLUX Boyshort

holds 4 tampons' worth

Comfort is at the very top of the list with our Boy Briefs.  

Featuring our classic elastic logo waistband, full of stretch and softness. Boy Brief rest at the perfect place so you can feel comfortable throughout your whole period. 

Boyshort holds 4 tampons' worth so you can feel covered no matter what your flo'. 

FLUX Boyshort


Holds 4 tampons' worth


Interior: 50% Modal 50% Organic Cotton, Exterior: 82% Nylon 18% Lycra, Trim: 100% Polyester

Please note: Beige Bikini is on pre-order and will be shipped within 1 week



Give 'em a quick rinse 🚿


Chuck 'em in a mesh laundry bag before popping them into the machine on a cold wash 👌🏽


Hang to dry outside or inside! ✌🏿

PS: Don't use bleach or fabric softener ⚠️

Customer Reviews

Based on 11 reviews
Flow: Super Heavy
Products used: FLUX Undies, obvs!
Changing the future for menstrual protection

Ever since I heard about the idea of period pants I knew I had to get my hands on a pair but before the existence of FLUX it meant having to pay a hefty amount of custom charges which put me off. As someone who experiences extremely heavy periods I was also a bit sceptical if they would work for me. About a year later I found out about FLUX in the UK. No crazy custom charges AND they hold double the amount of blood than their competitors without paying more. It seemed a no brainer to me, I just had to buy some! I bought two styles the boyshorts and high waisted. I love having both styles because they provide me with different support whilst both working just as efficiently as each other. I particularly love wearing my boyshorts at the beginning of my period for that piece of mind that they are a snug fit and therefore have no problems with leaking. I still can't get around the fact that I can wear these for about 8 hours on day 1 and 2 before I feel the need to change them. Years ago that would mean changing a tampon at least 6 times in that 8 hours. They are so absorbing that when you go to wash them you won't believe how they manage to hold all the blood whilst remaining dry to wear- it's like magic! Having periods has been a nuisance to me before using FLUX but now it's no trouble at all! Get yourself a pair and you'll never look back!!!

Flow: Heavy
Products used: FLUX Undies, obvs!
A Revolution for Autism/Learning Disabled Girls

Despite being a bit cynical about Flux undies claims to being periodproof, we bought some trial pairs for our teenage daughter who is severely learning disabled, and often overwhelmed by the many skills required to manage periods independently. We’re three periods in now, and we’re not looking back. These pants are absolutely amazing - they really work. You get your period, you put your Flux undies on, you take them off a few hours later. And that’s it! When I think of all the skills we have been painstakingly teaching over the last few years - peeling off sanitary towel stickers, sticking pads in accurately, knowing when & how to remove them etc etc, it feels like the dark ages. And yet these were only a few months ago! We cannot thank you enough. You have given our daughter a very real shot at independence & dignity. This means the world to us, and to her, and it’s one less thing we need to worry about when we plan for her future.

Flow: Super Heavy
Products used: FLUX Undies, obvs!, Disposable pads
So much more comfortable

I feel soooo much better when having my period.
I am comfortable wearing this even at my heaviest periods. It is tightening around the stomach and feels so much more comfortable than regular panties.
I do still wear them with a pad, really want to try them without one, I am sure they will work, but I haven't had the time yet.

Flow: Heavy
Products used: FLUX Undies, obvs!
Wish I had bought these earlier

I have heavy and quite long periods. For medical reasons I cannot use tampons so over the years I have used loads of disposable pads. I hate thinking about the amount of waste! I have tried using reusable pads but they didn’t stay in place and caused leaks. For the same medical reason I cannot use menstrual cups so I was really hoping these Flux underwear would work....and they do! Easy, and comfortable.

Flow: Super Heavy
Products used: FLUX Undies, obvs!, Tampons, Menstrual cup
Don't know how I coped without

I have super super heavy periods. They're insane! Flux underwear has meant that I can still do things like rock climbing and running. They're also super comfy.

FLUX Undies are your complete replacement for pads and tampons and can be worn alone for up to 12 hours. 

 Our unique built-in tech is moisture wicking, absorbent, and leak-proof, keeping you covered day 'n' night. 

 Bikini offers full coverage without the bulk, and the soft lace waistband keeps you comfy in style. 

 - Wear all night, or for up to 12 hours during the day 

- Holds 20-25ml, more than any other product out there 

- Our customers use FLUX Bikini for periods, leaks, post-partum, and incontinence! 

- Wear them to school, work, for exercising, or simply just to feel comfortable on lazy days. 

 Find out more on how our undies work.

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FLUX Hi-Waist
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