Flux undies review: get 25% off with our EXCLUSIVE code
WANT to go plastic-free with your period? We’ve tested out Flux Undies to see if the sustainable brand offers a viable alternative to tampons and pads — and we’ve got an exclusive code for Sun Selects readers.
Period care has come a long way in recent years. The market is brimming with brands offering up period-proof underwear that you simply wear, wash and reuse, and thanks to their sustainability and toxin-free fabrication, they’ve pretty much revolutionised the way we approach that time of the month.
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Flux is one of several period underwear specialists that frequently appear on ‘best of’ lists, so we were keen to put them to the test and see how they hold up.
- Get 25% off Flux Undies with our exclusive code SUN25 – buy here
Pros
- Good choice of designs and flows
- Absorbant and keeps you dry for up to 10 hours
- Free from toxins and chemicals
- Cruelty-free certified
- Quick-drying, so feels more comfortable than pads
Cons
- More expensive upfront than buying a pack of tampons or sanitary towels
- We noticed a slight odour on our heaviest day
- Washing is a bit of a faff
- Takes a while to dry indoors
Flux undies review: quick summary
- Classic Bikini – Moderate Flow, £25.95 from Flux – buy here
We were sent three pairs of Flux’s undies to try: the cotton briefs in heavy flow, classic bikini in moderate flow and invisible cheeky pants in light absorbancy.
Our order arrived promptly and was packaged in a smart cardboard box with our three products in three further boxes. They were all recyclable and there was no plastic to be seen, as per the brand’s sustainable credentials.
This selection was pretty much spot on for the first three days of our period, so we were really pleased with the varying absorbancy of each. And we can genuinely say that each pair kept us comfortable and dry, with no leaks.
We did feel that on the heaviest day of our flow, the pants didn’t smell super fresh after several hours of wear. But we much prefer the idea of wearing pants that are free of toxins rather than containing synthetic fragrances.
Style-wise, all three knickers were comfy but the classic bikini is our absolute favourite: the lace trim is so pretty and makes you feel a bit ‘fancier’ while on your period.
Overall, would we wear Flux undies again? It’s a resounding yes!
Interested in trying Flux undies? Use the code ‘SUN25’ for a 25% discount, exclusive to Sun Selects readers – buy here
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Flux Undies review: full review
Unboxing and first impressions
Our Flux package was delivered by Royal Mail special delivery so it arrived very promptly. Flux offers free shipping on all UK orders but if you want yours sooner, it’s £6.95 for the next day service (order before 1pm).
The cardboard packaging features smart branding and is fully recyclable. It’s also pretty streamlined, which was handy for not overloading the communal recycling bin shared with the other flats in our building.
Upon opening the products, we were immediately impressed with the quality. The cotton of the briefs is nice and thick – even on the non-padded areas – so they feel like they’ll definitely last lots of wears.
The bikini pants are made from Tencel and felt really soft to the touch. Meanwhile, the invisible cheeky pants are an ultra-thin and seamless style that feels like standard no-VPL knickers — except for a very discreet built-in panel.
Performance
We roadtested Flux undies for the first three days of our period:
Day One
First up on day one was the heavy flow option, which we tried in the Essentials cotton brief style.
We found this to be a really comfortable design: it’s a simple, no-frills style that has a comfy stretch-elastic waistband with Flux branding. To be honest, the branding itself was already peeling slightly by the time we took the pants off, so we doubt it’ll last many washes… but that’s no biggie.
Designed for periods, leaks and incontinence, these pants promise to hold four tampons’ worth of blood and with frequent wear, should replace at least 200 single-use disposables.
They can also be worn for up to 12 hours, but we would say that after day-long wear on the heaviest day of your period, they do tend to have a slight odour. Perhaps this is inevitable with any period pant, though, as they contain zero fragrance or nasty chemicals, which is ultimately a win.
Most importantly, these pants kept us completely dry and leak-free while we wore them: the absorbency is great.
- Get 25% off Flux Undies with our exclusive code SUN25 – buy here
Day two
Next up was the moderate flow which we tested in the classic bikini style. We have to say this was our favourite pair of Flux undies. The cut is spot on, the fit is seriously comfy and the lace waistband adds extra ‘period belly’ hold while also looking really cute. It’s no wonder it’s a bestseller.
Thickness-wise, we thought the absorbent layers were ever-so-slightly more streamlined than the WUKA period pants we tried in a similar flow type.
And whereas the WUKA period pants had a slightly off-putting feel to the edge of the absorbent seam, these ones by Flux felt like they had less of a harsh line, so we were less conscious we were wearing period pants.
Once again, the absorbency was impressive (up to three tampons’ worth of blood) and we stayed dry all day.
Day three
Flux’s Invisible Collection is all about ‘ultra-thin, smooth, and seamless’ styles, making them ideal if you want to stay VPL-free while benefiting from a little hidden leak-proof protection.
In light absorbency, the invisible cheeky pants we tried hold two tampons’ worth of blood, so they’re great for the tail-end of a period — or even as an everyday knicker that’s pee proof.
We’d personally prefer a bit more bum coverage to feel totally secure on our period. We found ourselves double checking for leaks more than the other styles due to this.
But we loved the softness of the fabric: they felt like a second skin and were ultra-breathable.
Features and Design
Like all period pants, Flux undies use built-in tech to literally soak up your period. The triple-layer design has a moisture-wicking top layer to keep you dry, an absorbent layer, which (depending on the flow type) holds up to five tampons’ worth of blood and a final waterproof fabric that delivers total leak protection.
Meanwhile, the antimicrobial properties prevent bacteria from building up, which should prevent any unpleasant odours (although as mentioned, we didn’t feel 100% fresh on our heaviest day).
Each pair is designed to last for around three years, and there are eight different styles you can shop, from bikini to full brief.
Flow-wise, every woman’s period is different, so Flux has a choice of five absorbancies you can go for, which seems like a good range to us: there’s super-heavy, heavy, moderate, light or lightest.
How to wash Flux undies
Like most period pants, Flux undies simply require a rinse after use and then they can be popped on a normal 30 or 40 degrees wash. The only other thing to note is that you shouldn’t use any fabric softener (this can damage the absorbency) and they’re also not suitable for tumble drying.
Can you wear Flux undies for swimming?
Flux undies aren’t designed for swimming – the brand advocates wearing a tampon or menstrual cup. However, they can be worn for workouts, so make sure you check out the Flux activewear page.
How much are Flux undies?
Flux undies pricing starts from £16.95 for the seamless thong, with the most expensive product currently being the super heavy flow sleep short which comes in at £32.95.
However, to take the sting out of the price tag, you can use our exclusive code and get 25% off your order. Simply enter the code SUN25 at checkout.
Flux undies review: the verdict
We really rated the Flux undies we tested for comfort and breathability. As with any period underwear, the absorbent layer is nice and cushioned, so yes: you’ll be aware you’re wearing period pants. But they feel way better (and dryer!) than wearing pads.
Plus, you won’t have to worry about the risks of toxic shock syndrom (TSS) that tampons bring, as they’re free of toxins, chemicals and PFAS/PFOA.
On our heaviest day, we’d probably prefer to have a change of Flux undies on hand rather than wear the heavy flow briefs for the full 12 hours. That’s just personal preference – and we doubt that any period pant can realistically be completely odour-proof for that amount of time, so it’s no reflection on Flux.
Style-wise, the classic bikini style with lace waistband gets our vote for both comfort and aesthetic: we’d wear this design any day of the week!
The only downside with Flux is that there aren’t any multipacks where you can bulk buy and save. It’s therefore a little pricy upfront to get started, as you’ll want at least three or four pairs to save you from having to run a daily wash.
However, considering the period products you’ll be saving on buying in the long-term, the estimated three years of wear you get from each pair of Flux works out to be extremely cost-efficient. And that’s before you even consider the environmental benefits.
Overall, we’re giving Flux undies a big thumbs up. Its period pants are comfortable, stylish, eco-friendly, and best of all, kept us dry and leak-free on our period.
- Classic Bikini – Moderate Flow, £25.95 from Flux – buy here
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