Polymorphic Light Dermatosis – Causes, Symptoms & Treatment

Polymorphic Lichtermatosis

Polymorphic light eruption is a photodermatosis. The skin condition is widespread.

What is polymorphic light eruption?

Polymorphic light eruption is the most common skin disease caused by sunlight. It is also popularly referred to as sun allergy or light allergy, which is incorrect, however, because these terms do not exist in medicine. With a share of around 90 percent, polymorphic dermatosis is the most common disease of this type.

About 10 to 20 percent of the population suffer from it. The female gender is particularly affected by the skin problems. But the so-called sun allergy is also often found in children and young adults. There has been an increasing trend in recent years. Polymorphic light eruption is not an allergy in the classic sense because typical immune reactions and the formation of antibodies do not occur.

In Germany, the polymorphic dermatosis reaches its greatest distribution in the months of March to June, which is due to the climatic conditions. However, photodermatosis can occur at any time when traveling to areas where the sun shines frequently.


The exact causes of polymorphic light eruption are still not sufficiently researched. At least it is known that it is not an allergy, although the symptoms of photodermatosis are similar. Polymorphic photodermatosis is always triggered by unusually intense UV-A rays or UV-B rays. In most cases, this happens during the holiday season due to extensive sunbathing.In 75 percent of all people affected, UV-A radiation is responsible for the occurrence of the symptoms. In 10 percent, polymorphic photodermatosis is caused by UV-B rays. The other 15 percent suffer from a combination of both types of radiation.

Some scientists believe that polymorphic light eruption is caused by the immune system. A light-sensitive sensor is said to be present in the skin cells, which triggers photodermatosis. Other researchers, however, believe in an imbalance between oxidants and antioxidants within the horn-forming cells in the epidermis (upper skin).

This imbalance makes the people affected more sensitive to solar radiation. Sometimes polymorphic light eruption is also caused by taking certain medications.

Symptoms, Ailments & Signs

The typical symptoms of polymorphic light eruption usually appear with a delay. Symptoms such as itching , burning and reddish spots on the skin only appear a few hours or even days after exposure to the sun. In addition, nodules, vesicles or larger bubbles form. In some people, the skin also swells.

The symptoms of polymorphic light eruption present individually differently. In some patients, the redness can be very pronounced, while others suffer from significant itching. If a sun allergy occurs repeatedly, the symptoms are usually the same.

The symptoms of polymorphic light eruption often appear after prolonged abstinence of the skin. Therefore, it usually occurs in spring or when visiting the beach. It is typical that the symptoms only show up in areas of skin that have been exposed to intense solar radiation. Areas of skin that are particularly affected are the face, neck, décolleté, hands, arms and legs.

Diagnosis & disease progression

If polymorphic light eruption occurs repeatedly, it is advisable to see a doctor. The first thing to look at is the patient’s medical history. He would like to know about the course of the skin problems and when they occur. In this way he receives valuable information for making the diagnosis.

Furthermore, other possible reasons for the skin complaints must also be ruled out. Possible triggers are photoallergic eczema or insect bites . For a reliable diagnosis, the doctor irradiates a specific area of ​​the skin with UV light. This can be the upper arm, for example. If a polymorphic light eruption is responsible for the symptoms, the typical symptoms are triggered by this photo provocation.

Normally, the symptoms of polymorphic light eruption go away on their own after a few days without leaving any traces on the skin. However, the skin must not be exposed to any further UV radiation. If the skin is in regular contact with the sun, it will get used to the sun’s rays over time.

This eventually weakens the polymorphic light eruption so that skin reactions no longer occur. If it is a chronic photodermatosis, however, it must be expected to occur again in the following year.


Those affected by this disease suffer from various skin disorders. These primarily affect the aesthetics of the patient and can have a negative impact on them. It can also lead to inferiority complexes or reduced self-esteem. Children in particular can suffer from bullying or teasing with this disease and can also develop depression or other psychological problems as a result.The patient’s quality of life is significantly reduced due to the disease. This primarily causes a burning itch on the skin. Scratching can also lead to bleeding or scars. Blisters and pustules can also form on the skin and make everyday life more difficult. Furthermore, the patients with this disease suffer from a sun allergy, so that the affected person usually has to protect himself from the sun.

The risk of skin cancer is also significantly increased, so that those affected are dependent on regular checks and examinations. Treatment of the disease is symptomatic. Most complaints can be alleviated acutely. Furthermore, treatment with medication can significantly limit and reduce the symptoms. Complications usually do not arise.

When should you go to the doctor?

If those affected experience changes in their skin when exposed to sunlight, they should consult a doctor. If irregularities occur after sunbathing or a long walk, it is advisable to clarify the symptoms. If skin abnormalities develop at moderate temperatures and after spending a few minutes in the sun, the observations should be discussed with a doctor immediately.

Redness, pustules, swelling or blotches should be examined and treated. A doctor should be consulted if you experience a burning sensation on the skin, uncomfortable itching or blistering. If there are nodules or changes in the usual pigmentation, a doctor’s visit is advisable. Sterile wound care is required for open wounds.

If this cannot be guaranteed to a sufficient extent, a doctor must be consulted. Otherwise there is a risk of blood poisoning, since germs and other pathogens can get into the organism. This exposes the person concerned to a life-threatening situation that should be avoided. If additional emotional or mental problems arise due to the optical changes, a doctor is also required. Help should be sought if there is shame, withdrawal behavior, tearfulness or depressive phases. In addition to a visit to the doctor, it is recommended to consult a therapist so that the general state of health improves as quickly as possible.

Treatment & Therapy

Cooling the skin with yoghurt, quark or buttermilk is recommended to treat the symptoms caused by polymorphic light eruption. The cooling causes the blood vessels to contract, which reduces any swelling. In addition, the skin receives much-needed moisture, which promotes its regeneration.

If the sun allergy is severe, the use of medication can be useful. Antihistamines , which are administered as tablets or ointments, have a soothing effect on itching. Preparations containing cortisone are sometimes administered to counteract the inflammation on the skin.

Additional phototherapy is considered helpful. This takes place in spring or before a holiday trip and serves to gradually get the skin used to the sun through irradiation. The exposure to UV rays is continuously increasing.


Sufficient protection from the sun should be provided to prevent polymorphic photodermatosis in the first place. This includes sunscreen with a sun protection factor between 30 and 50, protective clothing and wearing a hat.


In acute cases, polymorphic light dermatosis can be treated with special creams or ointments. These creams should contain corticosteroids such as hydrocortisone. Very severe itching after sunbathing can also be relieved by taking antihistamines.

In order to prevent the symptoms of polymorphic light eruption, people with sensitive skin should gradually expose themselves to UV radiation in spring and summer. It is particularly advisable to do this weeks before the summer vacation so that the skin can slowly get used to the sun’s rays.

It is also possible to prevent the disease by protecting yourself with broad spectrum sunscreens during exposure to the sun. These should be effective against both UVA and UVB rays and have the highest possible sun protection factor. Preparations that contain the antioxidant alpha-glucosylrutin are also effective.

According to scientific studies, taking dietary supplements such as vitamin D3 in the form of omega-3 fatty acids can also improve the symptoms of polymorphic light eruption.

Prophylactic phototherapy can also prevent the development of a sun allergy. This involves repeated whole-body irradiation with blue light of a specific wavelength. A very last step and not recommended way of treatment is a so-called photochemotherapy. However, this therapy can cause long-term health risks for the patient.

You can do that yourself

The rashes and wheals that develop with polymorphic light eruption usually heal without any problems, but they are unsightly and annoying, sometimes even painful. Therefore, the patient will focus on avoiding UV-A light to prevent the disease from developing in the first place. Creams and lotions with a high level of sun protection also help to prevent hives from developing. If a rash does occur, the affected person can cool the areas. If possible, the areas should not be scratched so that the pustules cannot become infected with bacteria. Antihistamines and phototherapy help prevent further rashes.

In particularly severe cases, the quality of life of those affected suffers considerably. Psychotherapeutic treatment is therefore advisable in similarly severe cases . Those affected also benefit from relaxation techniques. Jacobson ‘s progressive muscle relaxation , yoga , qigong and tai chi are recommended. Music therapy can also bring some relief.

Self-help groups for people with polymorphic light eruptions did not exist for a long time. Self-help groups for people with light allergies have only been set up in recent years, when the disease has become more frequent. The first of these was the “Lichtblick” group in Schwerte, and other groups followed.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.