Boyshort - Heavy Flow
Boyshort style period underwear with elastic logo waistband
Boyshort style period pants with elastic FLUX Undies logo waistband
Boyshort style period pants with FLUX Undies logo waistband

Boyshort - Heavy Flow

Regular price £27.95
Tax included. Shipping calculated at checkout.

Get comfy on your period with our leak-proof Boyshort period pants, featuring our classic logo elastic waistband full of stretch and softness. With our signature built-in tech that is moisture wicking, absorbent, and leak-proof, Boyshort gives you the ultimate comfort and protection during your period, day and night.  

  • For periods, leaks and incontinence
  • Holds Four Tampons' Worth / 20-25ml
  • Wear For Up To 12 Hours Leak-Free
  • Soft, Stretchy and Comfortable
  • Lightweight and Quick-drying
  • OEKO-Tex Certified Materials
  • Free From Toxins, Chemicals and PFAS/PFOA

Materials: Body95% TENCEL Modal 5% Elastane Gusset: Absorbent Blend, Breathable PUL Packaging: 100% Recycled and Recyclable Cardboard

🍃 Bleed Green: Each pair of our period pants replace 200+ disposables from going to landfill, reducing your waste by 99.5%

🤝 Giving Back: For every purchase, we give back to a girl in need. Find out more about our #ByYouForHer giving back scheme here

We offer free shipping on all UK orders and free shipping on International orders over £75.
For same-day dispatch and next day delivery, please place your order before 1pm.
All orders are dispatched from our UK warehouse using trusted couriers such as Royal Mail, DHL and DPD. 
Think our period pants sound too good to be true? Take them on a risk-free trial for 60 days!

If our undies don't work as promised, let us know within 60 days and we'll refund you, no questions asked. The 60-day risk free trial applies to one worn pair of undies only. Refunds will be paid to the original payment method that was used to place the order.
🚿 Rinse after use.
🧽 Machine wash on 30-40 degrees.
 🍃 Hang to dry or dry indoors on a radiator.
⚠️ Do not use fabric softener or bleach. No tumble drying.
And that's it! Your FLUX Undies are ready to wear again!

Our Period Pants Are:

Sustainably Manufactured

We only use eco-friendly materials that are sustainably manufactured

Vegan and Cruelty-Free

Made from natural materials and never with animal materials or testing

Free From Nasties

Certified safe for skin and free from toxins, chemicals and fragrances.

60-Day Money Back Guarantee
How They Work

Our period pants absorb up to 5 tampons' worth of liquid, yet they look and feel just like regular undies.

Our built-in tech works like this:

1. Top layer wicks moisture away from the surface quickly, to keep you dry

2. Our middle layers absorb your blood and lock in your flow

3. The bottom layer pushes liquid back up and keeps you leak-free

It's simple. Just wear, wash and reuse.

Blood, Sweat, Whatever.

Three layers of fabric absorbing liquid showing how period pants work

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Customer Reviews

Based on 170 reviews
L. (Newport, GB)
Flow: Super Heavy, Heavy
Products used: FLUX Undies, obvs!, Disposable pads
Amazingly helpful

I'm a disabled transman who suffers from CFS. I grabbed the boy shorts after hearing about these undies on a youtube video and they have helped me out so much. Not only do they look good, but they are SO comfortable and the style of the undies has a very unisex vibe to them which helped combat my dysphoria <3
These undies really made my monthly so much more bearable, helped me not worry about my cycle and was really easy to use - my CFS thanks you FLUX!

E. (Oxford, GB)
Flow: Super Heavy, Heavy
Products used: FLUX Undies, obvs!
Another Great Purchase

I love these pants so much I have a collection of styles and absorbency types to see me through each period. I can’t recommend them highly enough. So much more comfortable than pads and tampons.

Kate (Welwyn Garden City, GB)
Flow: Super Heavy
Products used: FLUX Undies, obvs!

My daughter has very heavy periods and finds these better than other period pants that she has tried

Maria C (Hammersmith, GB)
Flow: Super Heavy, Heavy
Products used: FLUX Undies, obvs!, Disposable pads

I'm really impressed with these pants. I've tried several period pants and these are the best. I used it with pads during my period as I have a really heavy flow and without the beginning and ending of period. It didn't smell and although the pads leaked into the pants. It held it there. Really happy with them and will be buying more.

Claud (Newton Abbot, GB)
Flow: Super Heavy
Products used: FLUX Undies, obvs!, Disposable pads
Best night time period purchase

I have a super heavy flow, often having to get up 4 + times in the night to switch heavy duty pad. Slept the whole night through (minus minor unnecessarily panicked checks) without having to get up!

Miss Samantha Jade Nellist (Bradford, GB)
Flow: Heavy
Products used: FLUX Undies, obvs!, Disposable pads

Thought I’d buy a pair as I saw Steph Tom’s rave about these. Honestly they are the best thing I’ve bought. I use my pair at night at the moment and there was no leaking, super comfortable. They are a touch on the pricey side but 100% worth every penny. Will definitely be buying more