According to the Harvard Medical School, the most common sun allergies aren’t in fact allergies in the truest sense of the word. They’re actually a negative immune-system reaction triggered by sunlight, and the medical term for this is polymorphic light eruption or PLE.
What are the symptoms of PLE?
“Symptoms of PLE, which appear a few hours after exposure to sunlight, include itchy red papules on sun-exposed areas of skin,” says Antony R Young, Emeritus Professor of Experimental Physiology at King’s College London, whose research interests include mechanisms of UV-induced skin damage. In fact, an itchy or burning rash can appear later than that, with the NHS reporting cases of PLE two and even three days after sun exposure.
Those who suffer from PLE will recognise the most common areas of discomfort, which include the V of the neck, the back of the hands, and the outside surfaces of the arms and lower legs. More severe cases of PLE see hives and small blisters break out from the skin, which can even spread to areas beneath clothes.
If this sounds familiar, you’re not the only one as, according to Young, around 12% of the UK population wrestle with this debilitating problem. The condition’s more common in women than men, and it’s a particular issue for those with white skin, albeit can affect those with brown and black skin.
What causes PLE?
“It’s also more common the further you are from the equator,” says Young. That’s due to the greater proportion of UVA further from the equator, which tends to stimulate the rash. The sun emits two types of ultraviolet (UV) that reach our skin: A and B.
This we know. What we’re not certain of is the exact cause of sun allergies like this, actinic prurigo (which is more common among Latin Americans and the American Indian population), photoallergic reaction and solar urticaria. Some studies have identified a genetic component, others simply that your body launches a tidal wave of histamines after sun exposure.
How to treat PLE
While its irritating origins aren’t fully understood, the treatment is. “In most cases the rash is mild and self-limiting and quickly settles a few days after sun exposure without scarring,” says Young. “That’s if more sun exposure is avoided.”
If the rash is particularly itchy, it’s worth trying a non-prescription anti-itch cream that contains at least 1% hydrocortisone. Hydrocortisone is a steroid and works by dialling down your immune response. Antihistamines are another option, again to dampen down that urge to itch.
If you’re short of medical options, out on a sunny sojourn and PLE strikes, you can improvise by dipping some form of towelling material into a nearby stream and apply the cold compress to the affected area. Taking a full dip in cooling waters helps, too.
Can you prevent PLE?
As ever, prevention is better than a cure. Unfortunately, there’s no perfect prevention PLE remedy. There are, however, numerous measures that you can take to at least lessen the chances of an outbreak.
“The use of a very high sun-protection factor (e.g. SPF 50) broad spectrum may help to prevent PLE,” says Young, “though you might also in a stronger position come August as progressive reduction in symptoms during the summer – known as tolerance – is common.”
You could also spend more time in the shade when the sun’s at its strongest, which in the UK is usually between 11am and 3pm. Covering up helps, too, as does wearing a cap or visor.
All of this should ease and (hopefully) prevent sun allergies ruining your summer. “But if the symptoms persist and PLE is interfering with your quality of life, seek advice from a dermatologist,” Young says.
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