Shipping and Returns

We offer a 60-day money back guarantee. Try one pair of undies and if they are not leak-free as promised, you can get a full refund within 60 days. We accept standard returns/exchange of unused items in their original packaging within 30 days. In the case of receiving a faulty pair, please get in touch via email and we will be happy to resolve this for you!

Returning an item is easy, simply head to our returns centre here.

We ship worldwide! All orders are dispatched from our UK warehouse using trusted couriers such as Royal Mail, DPD, Fedex, and DHL.

All orders are shipped from our UK warehouse. Standard shipping is FREE on all UK orders and FREE on International orders above £75.

Next day and tracked shipping prices vary and further details can be found here.

Orders received before 12.30pm are dispatched same day and tracking information is sent via email same day.

Estimated shipping times and costs can be found on our delivery and returns page here.

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:

We are a UK based company and all orders are currently dispatched from our UK warehouse.

If you are ordering internationally, please check what taxes and duties may be applicable to you when you receive your order. We have no control over these fees and they are implemented by the customs department in your country.

For products purchased via our stockists, please contact that stockist directly to discuss your purchase.

How Do They Work?

Our leak-proof period underwear features unique built-in tech that is moisture wicking, odour-controlling, super absorbent and leak-proof, meaning they can be worn as a replacement for disposable period products and prevent leaks and stains.

They're made with super soft and ultra thin materials and they're so comfy that many of our customers wear them even when they're not on their period!

Depending on the style, our period pants can be worn for 8, 10 or 12 hours, completely leak-free. You will know when it’s time to change your FLUX Undies, but it will not be visible to anyone else!

Our period pants range come in five different absorbencies ranging from Lightest which absorbs 1 pantyliner or half a tampon to Super Heavy which can absorb up to 5 tampons worth.

To figure out which styles would suit you best, consider how light/medium/heavy your cycle gets throughout the week of your period and match it to one of our absorbency levels.

You can find out more on our absorbencies here.

Good question. The answer is no!

Every pair of our period pants uses clever materials that wick moisture from the surface to keep you feeling dry. We also use materials that are naturally anti-microbial and constructed to prevent bacteria building up, which means no smells!

Many new mums love using FLUX postpartum and for when their periods start to return. They can also be used in the weeks leading up to giving birth, for light leaks and incontinence. We also think our leak-proof underwear make a great gift for a baby shower!

They can! Our underwear comes in a range of different absorbencies and can absorb up to five tampons' worth of blood and be worn alone.

We recommend trying them at home first to get used to them and find out how they'll work for you.

All of our bodies are different and you know your flow best!

Product Info

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

No. Our underwear is free from toxins, chemicals, fragrances and PFOA/PFAS. No nasties here!

FLUX Undies completely 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're so confident you'll love them that we offer a 60 day money back guarantee so you can try them risk-free!

Whilst some brands of period pants use wool in their products, all of our products are and always will be 100% vegan and cruelty-free.

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. 

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

We believe in fair wages, good working conditions, a happy environment, and reasonable hours. Currently, our undies are made with love in China, by family run manufacturers with over 20 years experience. 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.


We'd love for you to sell our period pants and join us on our journey as we grow. For further information, head over to our wholesale page to get in touch or email us at

Care Guide

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 or 40 degrees, and hang to dry. Please do not tumble dry / add fabric softener - this can damage the absorbent tech. 

One pair of FLUX Undies will last 3 years+, replacing over 200 pads/tampons and stopping them from going to landfill! This is based on using a pair of underwear once during each cycle for three years. 

Don't worry, an accidental tumble dry will not ruin your underwear. However, remember to hang to dry as consistent tumble-drying can cause the absorbent tech to break down and result in a much shorter life span!

Affiliate - Spread The Word & Earn £££

Yes, we have both! To sign up and spread the word, please learn more here.


With Klarna, you can buy our period underwear now and pay for your order in 3 equal payments every 30 days — no interest added.

Simply add your products to the cart and at checkout, select the Klarna option and enter your debit or credit card information. No interest or fees. To check your eligibility, Klarna will perform a soft search with a credit reference agency. This will not affect your credit score.

Once we've shipped your order, Klarna will charge your card for the first instalment and send you a notification once the payment has been processed.

After you have made your first payment, Klarna will automatically charge your card every 30 days for the remaining payments. They will make sure you are informed ahead of time. There's no interest or fees.


Klarna orders are sent just like any other UK order and should get to you within 1-2 working days if you choose standard shipping, or next day if you choose next day delivery and checkout before 12.30pm!

You must be 18+ and a UK resident to use Klarna.

Our Mission

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, we donate to girls and people in need. Learn more about the charities and people we work with here.

Facts and Figs

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

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

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

Most people experience a blood flow between 10-80 ml during one cycle, and the average amount of blood that our body expels during menstruation is on average, 40 ml. That is about 2 – 3 tablespoons (42ml) or 6 teaspoons (30ml). While that is the average, people 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 *your* flow.

‘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 and giving back scheme.

Got more questions?

Send us an email at