ECZEMA
Why a workout amplifies eczema
Eczema is a chronic inflammatory condition of the skin barrier. At baseline that barrier is compromised: more permeable, drier, and quicker to react than non-eczematous skin. A workout adds four stressors that each exploit that.
Heat. Core temperature rises and blood flow to the skin increases, which makes the barrier more permeable still. Eczema-prone skin reacts more sharply than normal skin to the same rise.
Sweat. Sweat carries salt, urea and lactate. On an intact barrier that is harmless; on a broken one the salt alone can sting, and sweat pooled against a patch prolongs the irritation.
Friction. Fabric rubbing against thin, compromised skin causes micro-abrasion faster than it would on healthy skin, and each abrasion lowers the barrier further.
Chemical migration. Sweat behaves as a solvent. Loosely bound dye and finish chemistry can move off the fibre and onto skin that friction has already opened up, which is a classic route to a contact-dermatitis reaction layered on top of the eczema.
Every one of these is worse in a hot, non-absorbent, chemically finished synthetic and gentler in a breathable, absorbent, audited natural fibre.
Why polyester is the hardest fabric on eczema
Polyester dominates performance activewear, and its whole construction works against a compromised barrier.
It starts as petroleum, is polymerised with an antimony catalyst, and, because the fibre will not take water-based dye, is coloured with disperse dyes, the exact class dermatologists patch-test for textile allergy. Being hydrophobic, it cannot absorb sweat, so it holds it against skin and keeps the microclimate warm and wet. That warm-wet layer grows more bacteria, and eczema flares are well documented to worsen with bacterial overgrowth, particularly Staphylococcus aureus. To manage the resulting odour, many pieces add an antimicrobial coating, another documented sensitiser. Dermatology guidance for eczema consistently advises against polyester next to skin in warm or sweaty conditions, and the chemistry explains why.
What the evidence actually supports
The fabrics that recur in dermatology guidance and trials for eczema-prone skin, with what each one is and how it is made:
Organic cotton (GOTS). A soft, absorbent, breathable fibre, and the most-cited fabric in eczema guidance. The important part is the processing: GOTS bans the chlorine bleach, formaldehyde resins, restricted disperse dyes and heavy metals that a conventional cotton finish can carry. "Organic" describes the farming; GOTS is what cleans the dyehouse. Cotton's honest weakness is that it holds water once soaked, so on long, sweaty sessions it can stay damp.
Superfine merino. For years, guidance told eczema patients to avoid all wool. Superfine merino, around 17.5 microns or finer, changed that. Randomised trials in children and adults found that wearing superfine merino base layers next to skin lowered eczema-severity scores compared with participants' usual clothing, including cotton. Merino wicks sweat as vapour and needs no antimicrobial finish. The caveats: most machine-washable merino is treated with a chlorine-Hercosett process that coats the fibre in a thin resin and produces AOX wastewater, and it costs several times cotton with fussier care.
TENCEL lyocell. Wood pulp dissolved in NMMO, a non-toxic solvent recovered in a roughly 99.8% closed loop, spun into a very smooth filament that is gentle and well tolerated. Less hard-wearing than cotton, and only the branded fibre guarantees the closed loop.
Silk. Smooth and low-friction, used in some eczema-specific garments, but too delicate for most training.
The fabrics that recur on the avoid list: polyester and nylon (heat, trapped sweat, disperse dyes, bacterial load), coarse untreated wool (high micron count prickles), and standard bamboo viscose (open-loop carbon-disulphide processing with residue concerns).
Reading a label for eczema-friendly activewear
- Dominant natural fibre, with any elastane in single digits and core-spun so it does not touch skin.
- Certification: GOTS for organic cotton (fibre plus processing) or OEKO-TEX Standard 100 (finished-product residue limits). This is the strongest single signal that the flare triggers have been checked for.
- No antimicrobial or "odour-control" coating, usually silver or a biocide, and a documented sensitiser.
- No added moisture-wicking finish on synthetic, sometimes fluorochemical. Cotton and merino manage moisture without one.
- Wash before first wear to shed loosely bound surface chemistry.
Where LAINE HILL sits
LAINE HILL is 92% organic cotton with 8% elastane, core-spun so cotton is the surface even at the waistband, band and seams. We exclude the chemistries that eczema guidance flags: no antimicrobial coatings, no formaldehyde resin, no restricted disperse dyes, no heavy-metal pigments above accepted limits. We are not GOTS-certified yet. Formal certification is on our roadmap, and until we hold it we will describe what we exclude rather than imply an audit we do not have.
We did not design specifically for eczema, and we are honest that for sweat-heavy or outdoor training superfine merino may suit some eczema-prone skin better than cotton does. What we can defend is that cotton dominance, audited chemistry and core-spun construction are the same combination dermatology guidance describes for gentler next-to-skin wear.
If you have been training through repeat flares in polyester, the experiment is small and low-stakes: wear one clean-chemistry cotton piece for a couple of weeks and watch the flares. The LAINE HILL set is what we built for that test. We make no medical claims. We are offering the cleanest fabric we can stand behind, in a category that mostly does not bother.
Common questions
Can workout clothes make eczema worse?
Yes. Heat, sweat, friction and chemical residue from fabric finishes all aggravate a compromised skin barrier, and a workout amplifies all four. Polyester is the worst case because it traps heat and sweat against skin, hosts bacteria more readily, and carries disperse-dye and finish chemistry that sweat can mobilise onto skin. The fibre against your skin, and how it was dyed and finished, is what decides.
What is the best fabric for eczema during workouts?
For most people, GOTS-certified organic cotton with a small percentage of elastane: a gentle fibre with the antimicrobial coatings, formaldehyde resins and restricted disperse dyes audited out. But the evidence does not crown cotton alone. Randomised trials found superfine merino base layers improved eczema severity compared with usual clothing, including cotton. Merino just costs more and needs careful washing. TENCEL lyocell is another very smooth, gentle option.
Is bamboo good for eczema?
It depends entirely on the type, and the label rarely tells you. Bamboo lyocell is made in a closed-loop process with a non-toxic solvent and is gentle, comparable to TENCEL. Standard bamboo viscose is made by dissolving pulp in carbon disulphide and sodium hydroxide in a largely open loop, and residue concerns make it a weaker choice for reactive skin. If a label says only "bamboo", assume viscose.
Should I avoid all synthetic fibres if I have eczema?
Not all. Low-percentage elastane, core-spun so cotton is the surface against skin, rarely triggers flares. Polyester as the dominant next-to-skin fibre is the real problem, because it stacks heat, trapped sweat, bacterial load and disperse-dye chemistry against an already-permeable barrier. What touches your skin matters more than what is buried inside the yarn.
