Sun allergies are very common, especially among young women and people with fair skin. This article looks at the causes and symptoms of PLE and other reactions to the sun, as well as explaining how to prevent sun allergies and protect allergy-prone skin.
Can you be allergic to the sun?
Yes - sun allergies, also known as photodermatitis, are an immune system reaction to sunlight which most often appears in the form of an itchy red rash. Sun exposure without adequate protection is harmful to our skin and can cause sunburn, but for some this exposure results in a more extreme reaction.
The most common form of sun allergy is polymorphous light eruption (PLE), also known as polymorphic light eruption (PMLE). ‘Polymorphic’ refers to the fact that the condition can appear in various forms - ‘poly’ means ‘many’, and ‘morphic’ means ‘forms’.
PLE affects between 10-20% of the population in western countries. This sun allergy tends to be more common in the spring or early summer. Polymorphous light eruption is not infectious.
PLE symptoms range from a mild rash to small red bumps, pustules and blisters. Skin is nearly always itchy regardless of the appearance. A PLE rash normally appears on areas recently exposed to sunlight, such as the underside of the arms and chest, and the backs of hands, legs and feet. Facial skin can be affected, but this is less common.
These areas of skin are commonly covered by clothing in winter, so many polymorphous light eruption sufferers often experience symptoms each year when skin is first exposed to strong sunshine, or when visiting countries with warm climates. Repeat episodes of PLE are less likely as the summer progresses.
In some cases just 30 minutes of sun exposure is enough to trigger PLE, although for most people their sun allergy rash develops within hours, or up to two to three days after exposure. The rash normally clears within two weeks upon no further sun exposure, healing without scarring. Further sun exposure may result in a worsening of sun allergy symptoms.
When to see a doctor
If you develop a skin rash with no obvious cause, such as a known allergy or contact with poison ivy, you should seek medical advice.
Rashes caused by polymorphous light eruption look similar to rashes linked to other serious diseases, so you should get a prompt diagnosis. See a doctor if your rash is painful, widespread or accompanied by a fever.
What causes sun allergies and PLE?
Direct sun exposure triggers sun allergies and PLE due to its UV light component. Similarly, symptoms can also be triggered by indirect light exposure such as that from sitting by a window or from wearing thin clothing outdoors.
Exactly how these triggers cause PLE is not fully known but research suggests that it may be due to an inherited genetic disposition, so it can run in families. Around one in five people with PLE have an affected relative.
When people have the underlying condition, their immune system identifies areas of skin altered by the sun and reacts against this, causing a rash.
- UV light rays – especially long wavelength UVA rays (which trigger PLE in 80% of people affected) – penetrate deeply into the skin where they can damage cells.
- UV-induced free radicals form highly reactive chemical compounds which cause oxidative stress, resulting in cell damage.
- People with PLE have an impaired cellular defense which reduces their skin’s ability to handle these free radicals.
- On exposure to the sun their skin responds by over activating its immune function, resulting in red and inflamed skin.
Some medications such as antibiotics and antihistamines are also known to cause skin sensitivity which can exacerbate symptoms in sun allergy sufferers. If you are concerned that your medication may be influencing your PLE, seek advice from your doctor or other relevant medical professional.
Treatment and prevention for sun allergies and PLE
Whilst there is no cure or treatment to get rid of sun allergies such as polymorphous light eruption, symptoms can be prevented or reduced by careful sun protection. Limit your exposure to the sun by avoiding the peak hours when it is at its most intense (between 11am-3pm).
Wear protective clothing, and use a sun protection product that offers high or medium protection against UVA, UVB and HEV light, and that has been specially formulated for your skin type and condition.
Sunscreen should be applied generously prior to sun exposure, and should be reapplied frequently to ensure your skin’s protection, especially after swimming, perspiring or towelling.
You can read more about how to minimise the risks of exposure, how to choose the right sun protection products for your skin and how best to apply them in How should I protect my body from the sun? and How much sunscreen should I use?.
Eucerin Sun Creme-Gel Sun Allergy Protect SPF 50 is a light, non-sticky sunscreen that has been specially formulated for skin prone to PLE and sun allergies.
Eucerin’s Advanced Spectral Technology combines broadband and photostable UVA/UVB filters1 with Licochalcone A to neutralise free radicals caused by UV and HEV light. The formula also contains Alpha-Glucosylrutin which helps to prevent sun-induced allergies and is unperfumed to minimise the risk of skin irritation. It can be used on both your face and body.
For severe PLE, a dermatologist may recommend a topical steroid cream or a course of prophylactic light therapy. This treatment gradually exposes skin to UV rays in order to build up a tolerance of sunlight.
Those with milder PLE often find that the condition gradually improves as the skin becomes more resistant to sunlight, and over time it may even disappear completely.
- Meeting the high standards for UVA and UVB protection defined by Cosmetics Europe. The levels of UVA protection are higher than the EU recommendation.
Severe or persistent rashes may require treatment with medication.
How to treat skin prone to sun allergies
If you are suffering from PLE, the first thing to do is avoid further sun exposure. Further contact with the sun can make the sun allergy rash flare up even more. Wear clothes that hide the affected body parts.
Eucerin Sensitive Relief After Sun Cream Gel soothes and supports the regeneration of sun-stressed skin, as well as relieving sunburn. Unperfumed, to minimise the risk of skin irritation, this is clinically and dermatologically proven to be suitable for sensitive skin, as well as skin prone to sun allergies.
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