your questions, answered.

about the undies

How does FLUX Undies work?

FLUX Undies combines four layers of ultra-thin materials that are moisture wicking, anti-microbial, absorbent, and leak-proof so you can say goodbye to pads and tampons. FLUX Undies is also used for post-partum, bladder leaks, and discharge.

What do you mean by 'period-proof'?

Period-proof means that the lining of the underwear is designed to absorb moisture from vaginal discharge, sweats, bladder leaks, and periods, without leaking. Our underwear consists of four thin layers of protection that make this possible. 

Top layer:moisture wicking, so that you stay fresh as a daisy. 
Second layer:anti-microbial, keeping you squeaky clean. 
Third layer: absorbs moisture, so you don’t feel wet. 
Fourth layer:leak-proof, so you're worry free.

Can FLUX Undies replace pads & tampons?

Yes, FLUX Undies replaces pantyliners, pads and tampons. Our absorbent lining holds up to 10x its weight and absorbs moisture at rates 20x faster than cotton. This allows FLUX Undies to absorb up to 4x the amount of a regular pad and hold for up to 12 hours depending on your flow. You will know when it’s time to change your FLUX Undies, but it will not be visible to anyone else!

Can I use them for bladder leaks?

Yes, that’s why we say FLUX Undies is so versatile! They can be used for periods, post-partum, bladder incontinence, and bladder leaks.

What colour is the lining?

The lining in all styles and colours, is black.

How do I wash my undies?

FLUX Undies should be cared for just as any other underwear. Simply rinse after use until the water runs clear, then wash them at 30 degrees, and hang to dry. Please do not tumble dry / add fabric softener - this will damage the absorbent tech. 

Is FLUX Undies hygienic?

Of course. The built-in protective panel has natural antimicrobial and antibacterial properties, due to the way in which the blood is locked and prevents further microbe growth, so you will feel fresh at all times. 

How long can I wear them for?

FLUX Undies absorbs up to 4x the amount of a regular pad and hold for up to 12 hours, depending on your flow. You will know when it’s time to change your FLUX Undies, but it will not be visible to anyone else!

How is FLUX Undies different from other brands?

FLUX Undies replaces pads and tampons, and can be worn alone during even heavy periods rather than just acting as a back-up to a pad/tampon. We also offer a clever and easy way to change without stepping foot off the ground, in even the most inconvenient spaces, with our simple side clasps. 

What are flux undies made from?

Is FLUX Undies eco friendly and ethically made?

Did you know one disposable pad takes up to 500 years to decompose? Or that hundreds and thousands of pads & tampons enter our landfills annually? Well, now you do. And you can help to change this. By switching to reusable period solutions, you're reducing your carbon footprint and stopping waste from damaging our planet. 

Aside from being an environmentally friendly alternative, FLUX Undies is kinder to your skin. The materials we use are Oeko-tex certified, meaning they're free from any nasties and safe to put on your most delicate and intimate parts. Our undies contain no hidden nasties, chemicals, or irritants. 

Are your garments vegan?

They sure are! Whilst some period panties use fabrics such as wool, our undies derive from 100% fabric and 0% animals. 

Where are FLUX Undies manufactured?

We believe in fair wages, good working conditions, a happy environment, and reasonable hours.Currently, our undies are made with love by two family run manufacturers with over 50 years experience.Around 60% of our undies are manufactured by our friends in China, and 40% are made right here in the UK.Any factories that we partner with undergo extensive audits and are ISO and BSCI approved, and also usematerials that are Oeko-tex certified, meaning they're safe to use. We believe in fair trade, proper pay, rest breaks, and a good cup of tea. We don't believe in exploiting women in one country to empower them in another. You can sleep easy knowing your undies are made ethically.

How long will one pair last?

One pair of FLUX Undies will last at least 3 years, replacing over 450 pads/tampons and stopping them from going to landfill!

Sizing and styles

What size am I?

As sizing may vary slightly for every style, you can find waist and hip measurements, along with sizing conversions on each product's page. 

How many style/colour options are there?

Currently, we offer five different styles: Bikini, Boy Brief, Detachable, Hi-Waist and Thong. All styles are available in Black. To make sure you don't miss out on new styles, ranges, and colours, sign up to our newsletter and be sure to keep up with FLUX through our website and social media channels. 

Are the side clasps on the detachable style comfortable?

Our detachable style is designed to give you the ultimate freedom. On a long flight and need to freshen up in those *tiny* cubicles? We've got you covered. Our simple side clasps are practical and comfortable and have been specially designed to sit on your hips feeling as comfortable as the pants. We’ve chosen clasps that cannot rust, are skin-sensitive, and super comfortable. They’re so comfortable you won’t even know they’re there.

shipping and returns

How long will it take to receive my underwear after placing an order?

Your order should ship within 1-2 business days and arrive within 5-7 business days if you have selected standard shipping. Express shipping should arrive within 1-3 business days. You can find shipping times and prices for countries outside of the UK, here. Please note, if you have pre-ordered something, then the shipping date will have been indicated upon placing your order. You can also find more information and status updates on pre-orders, here

Can I order internationally?

Of course! FLUX Undies was made for women all around the world. You can find shipping rates and times, here.

I've just placed an order, but need to make a change. What do I do?

Orders are processed pretty quickly, but we will do our best to make any changes. The best way to request to modify or cancel an order, is to send us an email as soon as possible at: 

What is your return policy?

We offer a 14-day money back guarantee. If, for any reason, you are not happy with the underwear, you can return or exchange unused items within 14 days. If you have received a faulty pair, please get in touch via email and we will be happy to resolve this for you!


I'd love to sell FLUX Undies in my store. How can I do this?

We'd love for you to sell FLUX Undies and join us on our journey as we grow. For further information, please send an email to 


How does buying FLUX Undies help girls in the developing world?

We're committed to helping women and girls in developing countries, and through our 'By You, For Her' programme, for every pair of FLUX Undies bought by you, a girl in the developing world will receive a reusable, washable pad.   

How do you empower women and girls across the globe? 

We're on a mission to empower women and girls across the globe by breaking barriers and smashing the taboo. We get our customers involved with our photoshoots, rather than hiring models, because we believe in true representation and empowering others. We aim to be a truly inclusive brand, and as we expand and grow, we aim to do even more to empower women and girls.

model for flux Undies

Can I model for FLUX in upcoming photoshoots?

We'd love to have you on board! At FLUX Undies, we believe that every body is beautiful and deserves to be represented. That's why you'll find people from all walks of life in our photoshoots, all our photos are unedited. We love the skin you're in. If you'd like to hop on board, send us two recent photographs or your social media handle, and a short explanation of why you want to model for us to with 'MODEL' as the subject. PS: We give away freebies at all our shoots!

facts & figs

How many women experience those 'oops' moments?

9 out of 10 women in the UK have experienced leaks and accidents during their period, through bladder leaks and light incontinence.  

How many pads and tampons does a woman use through her lifetime?

The average woman will use between 14,000 and 18,000 disposable pads, tampons and pantyliners during her lifetime.

How many pairs of stained underwear does a woman throw away each year?

5 or more pairs of underwear are typically thrown away by one woman every year.

How much blood do women lose, on average, per period?

Most women experience a blood flow between 10-80 ml during one cycle, and the average amount of blood that a woman’s body expels during her menstruation is 35 ml. That is about 2 – 3 tablespoons (42ml) or 6 teaspoons (30ml). While that is the average, women have given varying reports from just a spot to over two cups (540ml!) in one menstruation. Every body is different, and that's why we like to say: go with the *your* flow.

What is period poverty?

‘Period poverty’ refers to having a lack of access to sanitary products due to financial constraints - something that many of us are lucky enough to probably take for granted. Women and girls in third world countries are greatly affected, however, this is also affecting girls right on our doorstep and having a serious affect on education, health and life in general for thousands of girls in the UK. That's why we started our 'By You, For Her' campaign.   

More questions?

Drop us a line at