Period & Bladder Leak Protection That Actually Works: NIXI Body Carla Cream Heavy Leakproof Knicker at £23

Period underwear has come a long way. The early iterations — bulky, uncomfortable, and barely functional — gave way to better designs, but many still fall short on the details that matter most: genuine heavy-flow protection, a flattering silhouette, and the kind of comfort that makes you forget you’re wearing them. The NIXI Body Carla Cream Heavy Leakproof Knicker gets all of those details right — and then goes further.

Next-level anti-leak technology that holds up to 20ml — the equivalent of 4 tampons. Created in collaboration with The Endometriosis Foundation, bringing genuine medical and lived-experience expertise to the design. A VPL-free, flattering high leg silhouette. A seamless waistband designed for comfort even when living with scars or stomas. Washable and reusable — better for you and the planet. And £1 of every pair sold goes directly to The Endometriosis Foundation. At just £23, it’s the period underwear that finally delivers on every promise.

About NIXI Body

NIXI Body is a British brand creating leakproof underwear that takes the needs of real bodies seriously — bodies that experience heavy periods, bladder leaks, discharge, and the physical realities of conditions like endometriosis. Their collaboration with The Endometriosis Foundation on the Carla knicker is not a marketing exercise — it is a genuine design partnership that has produced a product specifically calibrated for the needs of people living with endometriosis and other conditions that affect menstrual flow and bladder control.

The Technology — How It Works

The Carla Heavy uses a four-layer absorbent gusset system that holds up to 20ml — the equivalent of 4 tampons worth of blood:

• Body layer (75% nylon, 25% elastane) — the layer against the skin. Soft, smooth, and moisture-wicking, drawing fluid away from the body and into the absorbent layers beneath
• Lining (95% cotton, 5% elastane) — the natural cotton layer that provides comfort and breathability against the skin
• Middle absorbent layer (80% polyester, 20% nylon) — the core absorbent layer that holds up to 20ml of fluid securely, preventing leaks and keeping the surface layer dry
• Waterproof TPU layer — the final barrier that prevents any fluid from passing through to clothing. TPU (thermoplastic polyurethane) is a flexible, breathable waterproof material that provides complete leak protection without the stiffness or discomfort of older waterproof materials

The result is a knicker that can replace pads or tampons entirely for periods, bladder leaks, discharge, and sweat when exercising — providing leak-free protection for the full duration of wear.

The Design — Every Detail Considered

• VPL-free high leg design — a flattering silhouette that works under fitted clothing without visible panty lines. The high leg cut is both aesthetically considered and practically effective, providing the coverage needed for heavy flow protection while maintaining a clean line under any outfit
• Seamless waistband — designed for ultimate comfort, specifically for people living with scars, stomas, or sensitivities around the waistband area. The seamless construction eliminates the pressure points and irritation that conventional waistbands cause
• Size down recommendation — NIXI Body recommends sizing down in the Carla for the most comfortable, secure fit — a detail that reflects genuine understanding of how leakproof underwear needs to fit to function correctly
• Cream colourway — a neutral, versatile colour that works under light clothing and provides the visual reassurance that the knicker is clean and fresh

Real-Life Usage Situations

🤎 Heavy Period Days — Complete Replacement for Pads & Tampons

The Carla Heavy’s 20ml capacity makes it a genuine replacement for pads and tampons on heavy flow days — not a backup, not a supplement, but a complete alternative that provides leak-free protection for the full duration of wear. For people with heavy periods, endometriosis, fibroids, or other conditions that cause significant menstrual flow, the Carla Heavy provides the protection that lighter period underwear cannot. Worn alone or as a backup to a tampon or cup for the heaviest days, it provides the confidence to move through the day without anxiety about leaks.

🏋️ Exercise & Active Days

The Carla Heavy’s leakproof technology handles the physical demands of exercise — the movement, the pressure, and the sweat that make conventional period protection unreliable during activity. The VPL-free high leg design works under gym leggings and activewear without visible lines, and the moisture-wicking body layer keeps the surface dry during exercise. For anyone who has experienced the anxiety of exercising during a heavy period, the Carla Heavy provides the freedom to move without restriction or worry.

💧 Bladder Leaks — Discreet, Dignified Protection

Bladder leaks — caused by stress incontinence, urgency incontinence, or the physical changes of pregnancy and postpartum recovery — affect a significant proportion of people at some point in their lives, and the stigma around them prevents many from seeking effective solutions. The Carla Heavy provides discreet, dignified protection for bladder leaks in a knicker that looks and feels like regular underwear, with no visible bulk, no rustling, and no compromise on comfort or style.

🌙 Night-Time Protection

Night-time period protection is one of the most challenging applications for conventional products — the extended wear time, the movement during sleep, and the horizontal position all increase the risk of leaks. The Carla Heavy’s 20ml capacity and waterproof TPU layer provide the protection needed for a full night’s sleep without the anxiety of waking to find leaks. The seamless waistband ensures comfort through the night without the pressure points that conventional waistbands create during extended wear.

🎁 The Thoughtful Gift for Period Wellbeing

Period underwear has become one of the most appreciated and thoughtful gifts in the wellbeing category — a practical, sustainable alternative to disposable products that demonstrates genuine care for the recipient’s comfort and wellbeing. The NIXI Body Carla Heavy, with its Endometriosis Foundation collaboration and £1 charity donation per pair, adds a layer of meaning that makes it a particularly considered gift. At £23, it’s a gift that will be used and appreciated every month.

The Value Case

The NIXI Body Carla Heavy delivers 20ml heavy-flow protection, a VPL-free high leg design, a seamless waistband, Endometriosis Foundation collaboration credentials, and a £1 charity donation per pair at just £23 — below the entry price of Thinx and Wuka, competitive with Modibodi and Flux, and with a design pedigree and charitable commitment that none of those brands can match. Compared to the ongoing monthly cost of disposable period products, a pair of Carla Heavy knickers pays for itself within a few months of use.

1,174 Units in Stock — All Sizes Available

Washable. Reusable. Better for you and the planet. £1 to The Endometriosis Foundation with every pair. The leakproof knicker that finally gets it right.

Care: Wash at 30º or 40º — no fabric conditioner. Air dry only — do not tumble dry.

Shop the NIXI Body Carla Cream Heavy Leakproof Knicker – £23 →