Most people managing eczema have been through the same cycle. You try a new moisturiser, switch to a gentler soap… See a GP, get a prescription cream, use it for a while, and things improve a bit.
Then the flare comes back anyway.
What almost no one thinks to check is the washing machine. Not because it's a secret, but because laundry detergent doesn't feel like a skincare decision. You put it in, the machine runs, the clothes come out clean. It doesn't seem connected.
But dermatologists have been flagging this connection for well over a decade, and the evidence has only grown clearer. The ingredients sitting in your detergent don't simply rinse away. Some of them are specifically designed to stay on fabric. And if you or someone in your household has eczema, what stays on your clothes after every wash cycle is in contact with already-compromised skin, all day and all night.
What's Actually Happening on Your Skin
Eczema affects around 1 in 5 children and 1 in 10 adults in the UK. One of the things that makes it so persistent is the skin barrier. During a flare, the outer layer of skin becomes dry, cracked, and significantly more vulnerable to outside irritants.
Under normal circumstances, healthy skin provides a reasonable defence against chemical exposure. With eczema, that defence is reduced, which means residues that most people could tolerate become a real problem.
There are two ways laundry detergent ingredients can affect eczema-prone skin.
The first is irritant contact dermatitis. This is a direct physical response, where a substance inflames or damages skin on contact. Surfactants, the cleansing agents in most detergents, are well-established irritants at sufficient exposure, and research has shown they can affect the skin barrier even in people without eczema. For those who already have a compromised barrier, the effect can be more significant.
The second is allergic contact dermatitis, where the immune system develops a specific allergy to a chemical and triggers a reaction whenever that chemical makes contact. This matters because allergic reactions can look identical to an eczema flare, which means some people manage what they believe is eczema, when it's actually an allergy to something in their washing powder that's never been identified.
UK dermatology clinics have documented this extensively. A large multicentre study found that more than half the patients who tested positive for allergy to MI, a preservative found in most mainstream laundry detergents, already had eczema. The two conditions don't just coexist. One makes the other significantly worse.
The Ingredient That Caused a UK Allergy Epidemic
MI is a preservative used in liquid detergents, fabric conditioners, and a wide range of other household cleaning products. It keeps products from developing microbial growth during shelf life but it also happens to be a strong skin sensitiser.
In 2010, fewer than 2% of patients at UK dermatology clinics tested positive for MI allergy. By 2013, that figure was above 11%. This is exactly the period when MI started appearing in more household cleaning products.
The reaction from dermatologists across the UK and Europe was swift. They called it an epidemic, and regulators eventually agreed, restricting MI in cosmetics and personal care products. Your shampoo and moisturiser now have to meet strict limits on how much MI they can contain.
However, your laundry detergent doesn't.
This is because they say that detergent rinses away, so it doesn't count as something that stays on skin. The problem is that's not entirely true, and the clinical data reflects it. Even after the cosmetics restrictions brought overall MI exposure down, the latest UK dermatology data still shows meaningful rates of MI allergy among patients, with laundry products and fabric conditioners among the confirmed sources.
What Stays on Your Clothes After the Wash
Fragrance is the other major issue, and it's a more complex one than the label suggests.
When a laundry detergent lists "parfum" as an ingredient, that single word can legally cover hundreds of individual fragrance compounds. Some of these are recognised allergens in their own right, including linalool and limonene, two of the most common fragrance terpenes used in cleaning products.
Here's the part that surprises most people: linalool and limonene aren't particularly problematic in their original form. The issue is what happens when they oxidise. Exposure to air converts them into compounds that research has identified as genuine causes of allergic contact dermatitis. Products that have been sitting on a shelf, or opened and resealed repeatedly, can contain oxidised versions of these ingredients that are more reactive than what was in the bottle when it was first made.
This matters for eczema management because fragrance is specifically engineered to linger on fabric. Microcapsules in modern detergents are designed to deposit onto clothing fibres and release scent throughout the day. The persistence that makes clothes smell fresh for 48 hours is the same mechanism that means whatever fragrance compounds are in that detergent, including oxidised allergens, are sitting against your skin for the same 48 hours.
Under UK detergent labelling rules, brands are required to declare specific allergenic fragrance ingredients when they're present above threshold concentrations. But many brands still list only "parfum" and consider their obligation met. For someone managing fragrance sensitivity alongside eczema, that tells them almost nothing useful.
Who's Most Affected
The answer isn't just people who already have eczema, though they are clearly at highest risk.
Children are particularly vulnerable because their skin is thinner and absorbs more. The school uniform worn from 8am to 4pm, the pyjamas worn for eight hours overnight, the towel used every day after a bath… All of these carry whatever the detergent left behind, in sustained contact with skin that's still developing its barrier function.
But every member of the household wears clothes, sleeps in the sheets, and uses towels after a shower. So if the detergent is leaving reactive residue on fabric, the whole family is in contact with it.
What to Look for Instead
If you're managing eczema, these are the four most important things to look for in a laundry detergent:
No MI or MCIGiven the documented rise in sensitisation, and the EU's own restrictions in adjacent product categories, this is the most important one to eliminate. The ingredient should not appear anywhere in the formulation.
Fragrance-free, or fully transparent fragranceFragrance-free is the safest option for eczema-prone skin. If you want a scented detergent, the brand should disclose exactly which fragrance ingredients are present, not just list "parfum."
No optical brightenersThese are UV-reactive compounds designed to coat fabric fibres and accumulate across washes. They serve no cleaning function, they're not rinsed away, and they have been reported as contact allergens in clinical literature.
Dermatologically tested and hypoallergenicThese terms are only meaningful when backed by third-party testing. Look for the certification to be verifiable, not just a marketing claim on the front of the pack.
