Britain’s unexpected spells of hot weather are wonderful, aren't they?
But what about those for whom the unprecedented run of sunny days and occasionally stifling heat, especially at night, have caused them to break out in heatrash?
Hot weather can put the skin at risk from a host of irritants, including insects, sweat, bacteria and even suncream, so your memento of a hot summer is likely to be an irritating itch than an all-over tan.
There’s every chance that your heatrash might also be something more serious altogether – such as seasonal eczema or even light sensitivity.
So have you got a lingering heat rash, or is it something else – and how should you treat it? Here, we ask the experts.
Heat rash – or, to give it its medical name, miliaria rubra – typically appears as a patch of small, bumpy red spots, which can be sore or itchy. The condition is caused when sweat droplets get blocked in the skin’s sweat ducts, which is more likely to happen if skin is covered in make-up or thick products such as suncream.
Dermatologist Dr Anita Sturnham explains: “Sweat stops draining through [blocked] glands and instead leaks into the surrounding skin, where it causes an inflammatory reaction, resulting in a prickly rash, with red, very itchy little bumps.”
The condition normally clears up within a few days, but avoiding sweat-inducing situations, keeping cool and drinking plenty of water will help. Wearing loose cotton or linen clothing will also keep the skin cool, as can having cold-water showers with non-perfumed soap or shower gel.
For short-term relief, an ice pack wrapped in a tea towel placed on the skin for up to 20 minutes will cool the area and calm any swelling. Similarly, applying calamine lotion or taking an over-the-counter antihistamine may also help.
Even people who usually only suffer very mild eczema can experience flare-ups in the summer months when hot-weather hazards such as pollen, sweat, swimming pool chemicals and sun creams can trigger an angry rash that feels tight, burning and itchy.
Pharmacist Kate Taylor, of Lloyds Pharmacy, recommends trying to work out what irritants might be triggering the eczema and taking measures to counteract them. She says: “For example, swimming pools with high levels of chlorine can irritate sensitive skin.
“Be sure to shower and dry off as soon as possible after a dip, paying particular attention to folds of skin such as the inner elbows, and apply your usual eczema cream to help avoid irritation and lock-in essential moisture.
“You may also find that you need to apply cream more often during the day to provide a barrier against the elements.”
She suggests trying a sensitive skin deodorant with 0 per cent alcohol to minimise sweating, and using gentle allergy-prevention sun creams designed for use by people with skin conditions.
Read more: How to treat heatstroke symptoms
‘Sweat rash’ is a term used to describe a number of skin conditions triggered by sweat, including heat rash. One common type, intertrigo, is a yeast infection of the skin caused by the bacteria Candida albicans.
It affects areas where the skin folds, meaning sweat can become trapped in a warm environment with little circulating air, such as armpits, the backs of knees, between toes, in the groin and beneath the breasts. More common in people who are overweight, it appears as an angry, red rash on the skin’s surface.
Official NHS advice to avoid the condition developing includes keeping skin cool, dry and exposed to air and showering daily with a non-perfumed body wash. Doctors also recommend using a skin barrier cream to protect the area and avoiding wearing clothes which rub against the skin or non-breathable fabrics like Lycra and nylon.
If a rash occurs, the advice is to wash the area gently and pat dry, rather than rubbing to prevent spread of the infection. It is important not to scratch as it can lead to a serious infection if bacteria breaks through the skin.
Read more: How to keep cool in a heatwave
Polymorphic light eruption
Around one in 10 adults in the UK have a reaction similar to an allergy when they are exposed to the sun or UV light, called polymorphic light eruption (PLE).
The condition causes areas of small, red, bumpy spots – often confused with heat rash – or blisters, which turn into larger, dry, red patches, which can look like eczema. It can last for up to two weeks.
Dr Sturnham, who represents skincare brand Sebamed, says: “PLE is thought to be caused by UV light-altering a substance in the skin. The skin’s immune system becomes hyperactive, and this triggers an inflammatory rash, normally on the arms, chest and lower legs.”
PLE does not usually affect the face, which is one of the key ways doctors can tell the difference between it and heat rash.
The main treatment is avoiding the sun, covering up with loose clothing and wearing a suncream with an SPF of 30 or above. Severe rashes can be treated with antihistamines or steroid creams recommended by a pharmacist or doctor.
If you’ve been taking advantage of the heatwave to swim in lakes, rivers or the sea, then any signs of heat rash may be swimmer’s itch instead.
The condition – also known as cercarial dermatitis – causes a red, bumpy, itchy rash, sometimes with small blisters, which is the result of an allergic reaction to parasites.
Snails can release microscopic parasites into both fresh and saltwater which burrow into the skin when they come into contact with swimmers. Water all over the world can contain the parasites, even if it appears clear.
Dr Sturnham says: “I am seeing an increased number of sufferers of swimmer’s itch thanks to the weather this summer.
“The good news is that humans are not suitable hosts for these parasites so they don’t live for long, but they are present long enough for the microscopic larvae to burrow into the swimmer’s skin. This causes an allergic reaction in the skin which triggers the rash.”
A tingling or burning sensation can appear almost immediately or up to a few days after swimming, followed by red pimples within 12 hours which can develop into blisters.
Most rashes will clear up within a week and the condition can be treated with a 1 per cent hydrocortisone cream, which is sold over-the-counter without a prescription.
For relief from itching, cool compresses, antihistamines, anti-itch lotions and soothing bath products designed for eczema may also help.
So-called because it often affects athletes, jock itch is a fungal skin infection in the groin or armpits triggered by sitting around in sweaty clothes. It is caused by a group of fungi known as dermatophytes that normally live problem-free on the skin.
But prolonged exposure to moisture – such as staying in sweat-soaked clothes or not changing out of wet swimming shorts or costumes – can cause the fungi to quickly multiply and cause infection. Wearing tight underwear in hot weather can also trigger the pink or red, itchy rash.
The bacteria, which also cause athlete’s foot, cause a highly contagious infection that can be passed on to others through bodily contact or unwashed clothing.
It can be prevented by washing daily with soap and water, drying off carefully and changing out of damp clothes as soon as possible.
If an infection sets in, it can be treated with over-the-counter antifungal creams, powders or sprays. The area should be kept clean and dry and clothes and underwear should be washed every day.
Kate Taylor points out that with all rashes, if the condition fails to start improving or gets worse after a few days, you should see a pharmacist or your GP.
And you should seek immediate medical help if a rash occurs immediately after eating or being stung or bitten by an insect, or if you have a headache, fever, joint pain or flu-like symptoms as well as a rash.