UNDERskin™
wellness you can wear
Underdays is the first underwear brand to integrate clinically tested skin microbiome technology into everyday essentials. UNDERskin™ redefines underwear as the foundational layer of a modern wellness routine, powered by HeiQ Skin Care™.
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This item is currently available for preorder only.
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Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Preorder item
This item is currently available for preorder only.
Delivery estimate is
Your skin is under constant attack
Stress, pollution, hormones, over-washing — all of it disrupts your skin's natural microbiome. The result? Dryness, sensitivity, irritation, uneven texture.
UNDERskin™ fights back, while you do nothing
Prebiotics + probiotics infused in the fabric transfer to your skin on contact. They restore balance, boost your native good bacteria, and promote a healthier, smoother skin appearance. Powered by HeiQ Skin Care™, Swiss synbiotic technology.
key benefits:
rebalance
radiance
protect
nourish
consistent
effortless
STEP 1
We infuse it in
Prebiotics + probiotics are embedded into the fabric within a 100% biobased slow-release matrix during production.
STEP 2
You put it on
When the fabric touches your skin, the synbiotics transfer naturally. No activation needed, just skin contact.
STEP 3
Your skin benefits
A more balanced microbiome means healthier-looking, smoother, softer skin. And it lasts up to 40 washes.
frequently asked questions
Our Everyday Collection is treated with HeiQ Skin Care™ — Swiss synbiotic technology that supports your skin's microbiome through fabric-to-skin contact. Underwear that works like skincare. It's a cosmetic treatment that promotes healthy skin appearance, not a medical product, it doesn't diagnose, treat, or prevent disease.
No, it's already built in. HeiQ Skin Care™ is embedded directly into the fabric during production, so it's working from the very first wear. No creams, sprays, or steps required.
No change to handfeel, breathability, colour, or fit, it feels exactly like the Everyday you already love. Non-irritant, human skin patch tested, and all ingredients INCI-listed.
Up to 40 washes. Wash at 30°C on a gentle cycle. Data provided by HeiQ based on testing conducted on other materials.
Not at all. UNDERskin™ is an addition to your routine, not a replacement, use it alongside your existing products.