Third heatwave of the summer, and the whole country has opinions about it. Trains crawling along at half speed, everyone suddenly an expert on cross-ventilation, ice lolly wrappers in every bin. If your skin flares at the slightest thing, though, you're dealing with something the weather presenters never mention: the prickle that starts behind your knees on the walk back from the shop, the itch that switches on the second you break a sweat, the flare that arrives two days into every warm spell as if it owns a calendar. An eczema flare up in heat isn't bad luck, and it isn't in your head. There's a chain of very physical reasons hot weather sets flare-prone skin off. Understand the chain, and you can break a few links in it.
The heat, sweat, itch chain, explained
Plenty of people assume winter is the villain, all radiators and biting wind, then get caught out when their eczema is worse in summer. The National Eczema Society lists heat and sweating among the most common flare triggers, and once you look at what sweat actually is, that makes sense.
Sweat is mostly water. The rest is salts, and that's where the trouble starts. On a hot day the water evaporates almost as fast as you produce it, and the salts stay behind on the surface of your skin. Skin with a sturdy barrier barely notices. Skin with a fragile barrier (which is what flare-prone skin is) has tiny cracks for those salts to settle into. It stings. You scratch. The scratching opens the barrier further, which lets more moisture escape, which makes the skin drier and itchier, which makes you scratch. Round and round it goes. Sweating and itchy skin aren't a coincidence, they're a mechanism.
Heat adds its own layer. Warm skin is itchier skin, because warmth makes the nerve endings that carry itch signals chattier. And sweat doesn't spread itself out politely. It pools where skin meets skin: elbow creases, backs of knees, the neck, under a waistband. Exactly the places flare-prone skin already struggles. Add damp fabric rubbing on damp skin and you have the full chain: heat, sweat, salt, itch, scratch, flare.
Underneath it all sits the slow-motion problem: dehydration. A heatwave pulls water out of your skin the same way it pulls water out of the lawn. A healthy barrier holds most of it in. A leaky one doesn't. So while everyone else's skin is merely a bit sweaty, yours is losing moisture at both ends, sweating it out and evaporating it away. Dry skin is itchy skin. That's why the flare often lands on day two or three of a warm spell rather than day one.
The summer extras nobody warns you about
Heat and sweat would be manageable on their own. Summer brings friends.
Sun cream. You need it, and we're not for one second suggesting otherwise. But plenty of sun creams carry fragrance and alcohol, and on cracked or flaring skin they can sting like a wasp. If sun cream sets your skin off, try a fragrance-free mineral one, and test it on a small patch of forearm (yours or your child's) before painting it everywhere. A pharmacist can point you at gentler options, which is a better use of five minutes than reading the back of every bottle in the big-brand aisle in Boots.
Cold, dry air on demand. Air conditioning is the radiator of summer: it makes the room comfortable and dries the air out at the same time. If you work in an air-conditioned office or drive everywhere with the fans on full, your skin gets a double shift of moisture loss. Outside in the heat, inside in the artificial dryness.
Grass and picnic blankets. Bare legs on a dry August lawn set a lot of people off, and grass pollen doesn't help those whose skin reacts to it. A blanket between skin and lawn is the easiest fix you'll read all week.
A realistic UK summer routine (nothing fancy)
Most summer skin advice is written for people whose skin behaves. This isn't. Here's a small dare while the heatwave lasts: run these five habits for one week and see what your skin says.
Shower lukewarm, and keep it short. A cold shower sounds tempting in this weather, and a hot one feels wonderful on itchy skin for about ninety seconds before it makes everything worse. Lukewarm is the boring, correct answer. It rinses away sweat salts without stripping the skin.
Pat dry, don't rub. A towel dragged across flaring skin is sandpaper. Pat, especially in the creases, and don't aim for bone dry. Slightly damp is what you want, because of what comes next.
Moisturise while the skin is still damp. The single highest-value habit on this list. Damp skin plus something to seal that water in beats dry skin plus the same product an hour later, every time. A simple balm does the job well. Our PureSoothe Eczema Relief Balm is five ingredients (calendula, shea butter, cold-pressed linseed and sesame seed oils, and a little beeswax), blended in small batches to soften rough patches and lock moisture into freshly showered skin. It's dermatologist tested, steroid free, and also suitable for skin prone to eczema. If you're weighing up what to put on your skin this summer, we've compared the options properly in our guide to the best natural eczema cream in the UK.
Dress in thin, loose cotton. Tight synthetic fabric traps sweat against the skin and rubs. Loose cotton lets sweat evaporate and moves with you rather than against you. And cut the labels out. You learned that trick from school uniform polo shirts, and it works just as well on holiday clothes.
Cool the bedroom before bedtime, not at bedtime. Curtains shut through the afternoon, windows open once the outside air is cooler than the inside, a fan if you've got one, a cotton sheet instead of the duvet. Overheating at night is one of the biggest drivers of night scratching, and night scratching undoes a whole day of good habits. If it's your child doing the scratching, we've written a full piece on how to stop your child scratching at night.
Paddling pools, chlorine and the sea: the honest version
We're not going to tell you to skip the paddling pool afternoon. It's August. Childhood is short.
Here's the honest picture instead. Chlorine dries skin out, whether that's the leisure centre pool or the pool on holiday. Paddling pool water is usually just the garden hose, but a whole afternoon in and out of it, sun cream mixing in, skin never quite drying, can leave things irritated all the same. Either way the answer is identical: rinse off with plain tap water afterwards, pat dry, moisturise. Rinse, pat, moisturise. Make it as automatic as reapplying sun cream.
Sea water is stranger. Some people find their skin genuinly seems happier after a swim in the sea. For others, salt water on cracked skin stings enough to bring tears. Nobody can predict which camp you're in, so on the first beach trip of the year, wade in slowly and pay attention. Whatever the verdict, the aftercare doesn't change: rinse the salt off, pat dry, moisturise while damp.
When it's heat rash, not eczema
Not every hot-weather rash is a flare. Heat rash (prickly heat) is a different thing: small raised spots, a prickling or stinging feeling, showing up where sweat gets trapped, and usually settling on its own once the skin cools down. The NHS has a clear guide to heat rash if you want to compare notes.
If you're not sure what you're looking at, ask. A pharmacist can often tell you over the counter. See a GP if a rash is spreading, weeping, blistering or hot, if your child seems unwell with it, or if flares are arriving harder and more often than they used to. For babies, your health visitor has seen every rash under the sun, literally. There's no prize for toughing out a mystery rash in a heatwave.
Your questions, answered
Why is my eczema worse in hot weather?
Three things stack up. Warmth makes itch-carrying nerve endings more reactive, so hot skin simply itches more. Sweat leaves salts behind as it evaporates, and those salts sting a fragile skin barrier. And hot weather dehydrates skin faster than usual, with air conditioning drying the air indoors on top. Sun cream and chlorine can pile in as extra irritants. It's a chain of triggers, not one single cause.
Does sweating make eczema worse?
For many people, yes. Sweat is mostly water, but as it dries it leaves salts on the skin, and those sting wherever the barrier is cracked. Sweat also pools in creases (elbows, backs of knees, neck) and adds friction under damp clothing. Rinsing with lukewarm water after sweating heavily, patting dry and moisturising straight away breaks most of that cycle before the itching starts.
How do I stop the itching in the heat?
Cool the skin instead of scratching it: a lukewarm shower or a cold flannel kept in the fridge works fast. Keep skin moisturised so the heat can't dry it into itching, wear loose cotton, and keep nails short so any scratching does less damage. If itching is wrecking sleep for you or your child despite all this, speak to a pharmacist or your GP.
That's the lot: lukewarm water, pat dry, moisturise while damp, cotton, a cool bedroom, and a rinse after every pool and beach trip. If you'd like one simple thing to keep by the shower this month, PureSoothe Eczema Relief Balm is our one and only product: five honest ingredients, hand-blended in small batches in the UK, made to soothe dry, itchy skin and lock in moisture through sweaty weeks exactly like this one. It's £27.99 for 50ml, rated 4.7 out of 5 by the 16 people who've reviewed it so far (we're small, we know), and covered by a 30-day money-back guarantee. UK delivery is £2.99 with Royal Mail Tracked 48, taking 2 to 3 working days, and free over £40, which two jars cover. Stay cool out there.