Polymorphic Light Eruption
Also often referred to as sun allergy or sun sickness, Polymorphic Light Eruption (PLE) is a skin rash that’s triggered by exposure to natural or artificial UV light – that is, sunlight or sun beds and tanning lamps. It’s thought to be an allergic reaction between UV light – both UVA and UVB rays – and proteins in the skin.
Experts believe PLE affects up to 15 percent of the UK population, which makes it a fairly common problem (two to three times more women are thought to be affected than men (i)). It usually starts between the ages of 20 and 40 and can run in families – according to the NHS, around 20 percent of people with PLE have another family member affected (ii). You can also have PLE whatever your skin type, though it’s thought people with fair skin are more commonly affected.
PLE is also thought to be more common in northern countries – such as the UK – and countries that aren’t very sunny. To learn more about how the sun affects your skin, see our helpful guide.
What are the symptoms?
The symptoms of PLE can vary from person to person. Some, for instance, may have an itchy or burning rash with small red bumps on their head, neck, chest and arms, while others may get blisters that turn into larger eczema-like dry red patches. Usually, the rash appears on parts of the skin that are kept covered during the winter – you’ll most likely experience a rash in the same area each time – and the face and hands aren’t normally affected.
The rash can be mild and may only last for seven to 10 days, but some people may suffer more severe and long-lasting symptoms that have a serious effect on their quality of life. Thankfully, when the rash fades it doesn’t leave any scarring.
Most people who are affected by PLE find their symptoms start in the spring after going out into the sun for the first time that year or during a winter holiday in a sunny climate. It can take as little as 20 minutes of exposure to UV light to trigger the rash, though many people find the rash starts a day or two after their initial exposure to the sun’s rays.
Staying in the sun after a rash starts will almost certainly make your skin worse. But the good news is that you may have fewer PLE episodes as summer progresses, as your skin adapts to being exposed to sunlight. You may even find your skin becomes less sensitive over the years, and you may eventually stop having rashes altogether.
Polymorphous light eruption FAQs
Is PLE only a problem if you go outdoors?
No, artificial forms of UV – including sun beds and tanning lamps – can also trigger a PLE episode. According to the British Association of Dermatologists, in some people even exposure to fluorescent lighting can cause PLE (iii). Experts also advise that some people can develop it by sitting next to a window when it’s sunny outside, or if they cover up in the sun but only wear thin clothing (ii).
What other light-related skin conditions might PLE be mistaken for?
There are some other disorders that your GP may want to rule out before diagnosing PLE. For instance, you may have a conditions known as chemical photosensitivity, where ingredients in cosmetic and medicated skincare products, certain medicines and perfumes trigger light sensitivity.
Or you may be affected by another sun-induced allergic reaction called solar urticaria, where your skin breaks out in raised red itchy welts within a few minutes of sun exposure. People who have an inflammatory disorder called lupus may also be affected by a bumpy rash on areas of skin that are exposed to sunlight. A rash caused by a skin reaction called erythema multiforme – which is usually triggered by the herpes simplex virus or a bacterial infection – can also look like a PLE rash.
If your GP refers you to a dermatologist, they may also try to reproduce your rash by testing your skin with different amounts and wavelengths of UV and visible light – a process called photo testing – to exclude other rare types of sun sensitivity.
Meanwhile, another condition that’s often mistaken for PLE is prickly heat. However, this is caused by warm weather and overheating rather than a reaction to UV light. Prickly heat also tends to affect the trunk, whereas a PLE rash usually develops on the head, neck, chest and arms.
Is PLE infectious, can it lead to skin cancer?
PLE isn’t contagious, so you can’t catch PLE from someone else nor can you spread it to another person. Experts also agree that having PLE doesn’t increase your risk of having skin cancer (iv).
Can avoiding the sun because you have PLE cause other problems?
Yes, there is a substantial risk that avoiding the sun altogether will make you deficient in vitamin D, as exposure to sunlight is the main source of this nutrient. If you don’t expose your skin to any or very little sunlight, ask your GP if you can have to your vitamin D levels checked. If the results show your levels are low, your GP may recommend that you take a vitamin D supplement as well as eat more foods that are high in vitamin D, including oily fish, fortified margarines and cereals, eggs and meat.
Treatments for polymorphic light eruption
There is no cure for PLE, but most people who are affected by it find their rash normally heals within a week or so if they stay out of the sun as soon as their symptoms start. You could also apply calamine lotion or use antihistamine tablets to help relieve itching, as well as take over-the-counter painkillers such as ibuprofen or paracetamol to relieve pain. Applying a cold compress – a towel dampened with cold water – or taking a cold bath may also be soothing.
Meanwhile, your GP may also recommend one or more of the following treatments:
A mild corticosteroid cream that’s available without prescription, this can also help to ease itching and soreness. Your GP may also prescribe a stronger steroid cream or ointment, which should be applied sparingly (carefully follow your GP’s instructions on how to use it). In some cases, a short course of steroid tablets may be necessary – for instance, these may be prescribed when you go on holiday to a sunny climate.
You may also be prescribed a high-factor sunscreen to prevent the rash from developing (use a product that has SPF30 or higher as well as a high UVA star rating).
Severe cases of PLE are often treated with tablets that are usually prescribed for malaria, such as hydroxycholoroquine. These treatments can reduce PLE symptoms, but the downside is they can trigger side effects in some people.
UV desensitisation/light therapy
Some people with more severe episodes of PLE may find increasing the resistance of their skin to the sun’s UV rays can help. If your GP thinks it may be useful, you’d have a course of desensitisation treatments at a hospital for around four to six weeks during the spring. This involves sitting in a phototherapy cubicle, where your skin is treated with increasing doses of ultraviolet light. Unfortunately, the effect of this type of treatment usually wears off during the winter months, so you may need further courses of treatment every spring.
Polymorphic light eruption: how to help yourself
If you’re affected by PLE, following the same sun safety advice that’s recommended for skin cancer prevention can help you to manage your symptoms.
Choose a high-protection sunscreen that has SPF 30 or higher with a four- or five-star UVA rating, and apply generously at least 15 to 30 minutes before going out in the sun (you’ll need around 35ml – or 6-8 teaspoons – of lotion to protect your body in a single application). Reapply sunscreen every two hours, or straight away after swimming and towel drying or if you’ve been perspiring.
Spend as much time in the shade as possible between the hours of 11am and 3pm when it’s sunny. If you’re outdoors, look for shade under trees and foliage, and if no shade is available create your own by using umbrellas, parasols, canopies and awnings.
Cover yourself up to protect your skin from the sun. Wear clothes made from tightly woven fabric that cover your arms and legs, and a wide-brimmed hat to protect your face (hold your clothes up to the light to get an idea of how much sun they let in).
You may also be able to build up your skin’s resistance to sunlight by going outside for short periods during the spring, gradually building up the time you spend outdoors. Start with just a few minutes of sun exposure and be careful not to overdo it.
To find out more on how to protect your skin from the sun, take a look at our guide.
This process is called hardening or toughening, and like UV desensitisation, the effects wear off during the winter – which means you’ll probably have to start the process again each spring.
Meanwhile, stay aware of how strong the sun’s rays are at any time of year – whether you’re in the UK or on holiday abroad – by downloading an app that tells you what the UV index is wherever you are.
For instance, if you have an iPhone or iPad, the UV Index Widget gives you the UV index forecast for the next seven days for any location in the world. You can download it for free from the App Store.
If yours is an Android device one of the top-rated UV apps available to you is UV Index Global. This gives you a five-day UV forecast and is free to download from the Google Play Store
Natural support for polymorphic light eruption
The following nutritional supplements may prove useful if you’re one of the many people affected by PLE:
If you have PLE you may avoid sunlight during certain times of the year in order to avoid having any symptoms. However, this may make you susceptible to low vitamin D levels, since the main source of vitamin D is sunlight (your skin produces vitamin D on exposure to UV light).
If you stay out of the sun to avoid the symptoms of PLE, you may need to take a vitamin D supplement (vitamin D is thought to be needed for bone health, reduced risk of heart attack and stroke, reduced risk of asthma and allergy, reduced inflammation and more).
In fact the UK government advises everyone to take a 10-microgram vitamin D supplement between October and early March. It also recommends taking a vitamin D pill to those who don’t venture outdoors very often or people who wear clothes that cover up most of their skin when they’re out and about during the summer too (v).
If you want to take a vitamin D supplement the recommended form is vitamin D3 (cholecalciferol), as this is the natural form of vitamin D our bodies make when we’re exposed to sunlight. You can get these in tablet form as well as in veggie-friendly drops. Most vitamin D3 supplements aren’t suitable for vegans, however, since they’re made from the fat of lamb’s wool. But the good news is you can get vegan vitamin D3 supplements available these days that are sourced from lichen.
A substance found in green vegetables, lutein is also an antioxidant that many natural health practitioners believe is also a type of natural sunblock. There is, in fact, some evidence that lutein may help protect against UV-induced skin damage (vi).
Green tea extract
Containing high levels of substances called catechin polyphenols – which are powerful antioxidants – green tea is also thought to help protect the skin from sun damage when applied directly to the skin (vii). It’s thought to work by protecting cells from some of the damage caused by UV light, rather than physically blocking it.
These are powerful antioxidants found in the pigments of dark and richly coloured fruit, such as blueberries, blackberries, raspberries and red grapes. They are often recommended to boost the integrity of the blood vessels, as they’re thought to help repair collagen in blood vessel walls and capillaries.
Polymorphic light eruption often goes undiagnosed, but this guide should make it easier to help to the bottom of your skin concerns. To discover more articles on a range of other common health conditions, why not visit our health library?
Available online: https://patient.info/doctor/polymorphic-light-eruption-pro#nav-1
Available online: https://www.nhs.uk/conditions/polymorphic-light-eruption/
Available online: https://www.bad.org.uk/shared/get-file.ashx?id=117&itemtype=document
Available online: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/
Roberts. RL, Green. J, Lewis. B. Lutein and zeaxanthin in eye and skin health. Clin Dermatol. 2009 Mar-Apr;27(2):195-201.
Katiyar. SK, Matsui. MS, Elmets. CA, et al.Polyphenolic antioxidant (-)-epigallocatechin-3-gallate from green tea reduces UVB-induced inflammatory responses and infiltration of leukocytes in human skin. Photochem Photobiol. 1999;69:148-153.
Elmets. CA, Singh. D, Tubesing. K, et al.Cutaneous photoprotection from ultraviolet injury by green tea polyphenols. J Am Acad Dermatol. 2001;44:425-432.
Disclaimer: The information presented by Nature's Best is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications.
Christine Morgan has been a freelance health and wellbeing journalist for almost 20 years, having written for numerous publications including the Daily Mirror, S Magazine, Top Sante, Healthy, Woman & Home, Zest, Allergy, Healthy Times and Pregnancy & Birth; she has also edited several titles such as Women’ Health, Shine’s Real Health & Beauty and All About Health.