FLUX Undies Period Pants Review

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When I was asked to review FLUX Undies period pants I jumped at the chance. I’m a big fan of eco-friendly period products, having used a menstrual cup for years before moving on to a menstrual disc.

But period pants were a new thing to me. I’d wanted some for a while, but I was nervous about buying a pair in case I didn’t like them.

There’s no denying that period underwear costs considerably more than regular knickers. And there are so many different brands and styles to choose from. I wanted to find period knickers that I loved.

Luckily, I hit the jackpot with FLUX Undies. These are the ones!

FLUX Undies Period Pants

Although I was gifted these period pants, my review is 100% honest and unbiased. I wasn’t paid to write this, and I’ll share with you the positives and negatives that I’ve found with FLUX Undies so that you can decide if they’re right for you.

But first, let me explain a little about these reusable period pants…

What are FLUX Undies?

FLUX Undies is a brand of period pants. These are reusable, washable knickers that you wear during your period instead of pads or tampons. They look just like normal knickers, but they absorb all of the blood.

Each pair of FLUX Undies can hold up to five tampons worth of blood, so you can wear them for up to 12 hours. Then, you simply rinse them and pop them in the washing machine.

FLUX Undies are manufactured using the most sustainable materials and environmentally responsible processes possible. So they’re great for the environment, as well as keeping our bodies free from chemicals and toxins.

Are FLUX Undies good?

Like most people who have never tried period pants before – I was a little apprehensive at first. I had some questions like –

  • Do period pants feel wet?
  • Do period pants get smelly?
  • Do period pants rustle?
  • Do period pants stain?
  • Etc etc etc!

I imagined period pants to be a bit like a nappy – thick, plasticky and constantly damp-feeling. However, FLUX Undies period pants are nothing like that at all! I stand corrected!

Firstly, FLUX Undies look and feel just like normal knickers – but better! When I reach into my underwear drawer for a pair of knickers, I can easily tell which ones are the FLUX Undies because they’re so much softer and nicer than all of my other underwear.

In the crotch area there are three layers of material:

  1. The soft moisture-wicking top layer that keeps you dry
  2. The absorbent and odour-controlling core
  3. The breathable and waterproof leak-proof layer

Despite the layers, I found FLUX Undies to be very thin and feel just as comfortable as my comfiest knickers.

A word on the sizing though – these can run a little small as they need to be a snug fit. I ordered my usual size 12 (medium) and found them to be too small around the legs, but the size 14 (large) fitted perfectly. So, if you’re not sure between two sizes, I’d say go for the larger one.

Washing FLUX Undies

When it came to washing my new period pants for the first time, I was a little nervous – was it going to be gross?

I needn’t have worried as I found washing the underwear to be simple. The two methods that work best for me are:

  1. Washing in the shower – This is ideal if you’ve been wearing period underwear overnight. When you get in the shower in the morning, you can use your feet to rinse them out before machine washing.
  2. Soaking in a bucket – If you’re in a hurry, you can just put the used pants into a bucket of cold water by the washing machine. Then, the next time you do a wash, just pop them in the machine.

After rinsing, you should wash FLUX Undies at 30 or 40 degrees. Avoid using fabric softener as this can make them less absorbent.

You can’t tumble dry FLUX Undies, so you’ll need to hang them to dry outside or on a radiator. As they look just like normal underwear, you shouldn’t need to worry about your neighbours taking notice.

The different FLUX Undies you can buy

I was so impressed with my FLUX Undies and I will be buying more pairs. I think I’d need about five pairs to use these throughout my period and have time to wash them.

FLUX Undies come in five different absorbencies:

  • Super Heavy
  • Heavy
  • Moderate
  • Light
  • Lightest

I tried the moderate flow pants, but I would like to get a variety for the different days of my period.

FLUX Undies come in so many styles:

  • Bikini – Light to Heavy Flow
  • Boyshorts – Light to Heavy Flow
  • Hipster – Moderate to Heavy Flow
  • Full Brief – Light to Heavy Flow
  • High Waist – Light to Heavy Flow
  • Thong – Light Flow
  • Sleep shorts – Super Heavy Flow

By mixing up a selection of absorbencies and styles, you can have the underwear you need for each outfit and each day and night of your period. There’s even a beige seamless thong that would be invisible under even the most see-through of clothing.

FLUX Undies give you a discount of 10% to 20% when you buy multiple pairs, so it’s worth stocking up on a full set.

With the 60-day money-back guarantee, trying FLUX Undies is risk-free. If you don’t like them, you get your money back.

FLUX Undies

Who should try FLUX Undies?

I think anyone would benefit from period underwear, but there are some groups of people who would particularly benefit…

  • Vegans – If you’re vegan for environmental reasons then this is a no-brainer. Disposable sanitary products take up to 500 years to decompose. Switching to FLUX Undies will reduce your waste by 99.5%. And of course, they’re 100% vegan and cruelty-free.
  • Anyone with bladder leaks – Not just for periods, FLUX Undies absorb discharge, sweat and urine. So you can jump on trampolines, laugh and sneeze freely without worrying about leaks.
  • Teenagers – Getting to grips with your period can be tricky and often involves embarrassing leaks. These leak-proof period pants are a much easier solution for younger girls.
  • Anyone who’s out the house all day – Reusables like menstrual cups often aren’t suitable for public toilets. As FLUX Undies can be worn for 12 hours, there’s nothing to do until you get home.

FLUX Undies Review

Jenni Fielding



I would 100% recommend FLUX Undies. These period pants are super soft, comfortable and really absorbent. When wearing these I would regularly forget that I’m on my period at all!


To conclude

I was very impressed with FLUX Undies. There are so many beautiful styles and colours to choose from in all different absorbencies. As an eco-conscious vegan, I love how these period pants are sustainably sourced and free from chemicals and toxins.

If you usually wear disposable pads, FLUX Undies are a game-changer and so much more comfortable! If you usually wear a menstrual cup, these are perfect for longer days out of the house or on the heaviest days of your period.

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