Many people experience itchy red rashes after spending time in the sun, often attributed to prickly heat. However, a common sun allergy called polymorphic light eruption (PLE) may be the actual cause, especially if you are taking certain medications such as atorvastatin or naproxen. In such cases, consulting a GP is advisable.
Dr Mark Porter, an experienced NHS GP with almost four decades of service, addressed this topic in a recent blog post on SAGA. He explained that classic prickly heat, known medically as miliaria rubra, results from blocked sweat glands and tends to occur in hot, humid environments rather than simply strong sunlight exposure.
“Your symptoms are more indicative of polymorphic light eruption (PLE), a sensitivity to sunlight, particularly UVA rays,” Dr Porter noted.
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PLE commonly causes an itchy, red rash that can develop within hours to several days after sun exposure. It is often mistaken for prickly heat, which might explain why some common advice, such as avoiding sunscreen, may worsen the condition. UVA rays can penetrate clouds, water, glass, and even certain clothing, affecting areas like the chest, tops of the feet, and arms, typically appearing on both sides of the body.
Prevention mainly involves reducing UVA exposure by using high-quality sunscreen - preferably SPF 50 with a five-star UVA rating - and reapplying every two hours. Avoiding direct sunlight during peak hours, generally between 11am and 3pm, is also recommended.
Dr Porter emphasised that newly initiated medications could potentially trigger photosensitivity reactions. Examples include some statins like atorvastatin, tetracycline antibiotics such as doxycycline, thiazide diuretics like bendroflumethiazide, and the anti-inflammatory drug naproxen. If you have recently started any of these medications and develop a rash, it is important to seek advice from your GP to evaluate their potential role.
While some dermatologists suggest beta-carotene supplements might help, the evidence is not robust. If used, a typical dose might be around 15mg daily, starting a week before increased sun exposure and continuing through the sunny period.
PLE most frequently first emerges in early adulthood, particularly among women in their 20s and 30s. This condition appearing for the first time later in life is uncommon. Although these medications may trigger or worsen PLE, this is not guaranteed; anyone concerned about their symptoms should consult a healthcare professional.
The NHS describes the rash associated with PLE as often affecting body areas not regularly exposed to sunlight, such as the arms, legs, or chest. A similar rash on the ears, sometimes accompanied by small blisters, is known as juvenile spring eruption and may cause itchiness or discomfort.
For further information, individuals are encouraged to visit the NHS website.