Sun allergy
and Carola Felchner, science journalistDr. med. Julia Schwarz is a freelance writer in the medical department.
More about the expertsCarola Felchner is a freelance writer in the medical department and a certified training and nutrition advisor. She worked for various specialist magazines and online portals before becoming a freelance journalist in 2015. Before starting her internship, she studied translation and interpreting in Kempten and Munich.
More about the experts All content is checked by medical journalists.Strictly speaking, a sun allergy is usually not a real allergy. Rather, the colloquial term describes various diseases that are triggered by a reaction to sunlight. What they all have in common is that the body's natural protective mechanism against UV rays fails and symptoms such as itching, burning, blisters or wheals occur as a result. Read what triggers a sun allergy and how it can be alleviated or even avoided!
ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. L56
Brief overview
- What is sun allergy? Usually not a real allergy, but a hypersensitivity to UV radiation in some other way
- Causes: not conclusively clarified; allergens or free radicals (aggressive oxygen compounds) are suspected
- Symptoms: variable: itching, reddening of the skin, blisters and / or blisters are common
- Diagnostics: discussion with the patient, light test
- Treatment: cool, provide with moisture, in severe cases possibly medication or habituation through prior irradiation by the doctor
- Prognosis: Over time, the skin gets used to the sun, so that the symptoms gradually decrease. Those affected by a sun allergy will never get rid of it completely.
Sun allergy: description
Typical symptoms of sun allergies such as itching and reddening of the skin are similar to the symptoms of "real" allergies (such as nickel allergy). Actually, a sun allergy is usually not a classic allergy, i.e. an overreaction of the immune system (exception: photoallergic reaction). Instead, the affected person's body can no longer adequately protect itself from the sun's rays.
Normally, the body reacts to sunlight with an increased production of skin pigments: This so-called melanin makes the skin look brown and protects the genetic material in the cells from the harmful UV-A and UV-B radiation in sunlight. In the case of a sun allergy, this protective mechanism of the skin is impaired. The consequences are, for example, itching, blistering or blistering or reddening of the skin.
With a share of over 90 percent, polymorphic light dermatosis (PLD) is by far the most common form of sun allergy. In Western Europe, around 10 to 20 percent of the population suffers from it. Young, fair-skinned women are particularly affected. Many children also suffer from PLD.
Sun allergy in children
Some children also suffer from a sun allergy. Small children and babies should generally be given a high sun protection factor before they are exposed to the sun. At this age, the body's own protective mechanism against UV radiation is not yet fully developed. As a result, the little ones get sunburn or a sun allergy faster.
The latter is most common in the face. The so-called "sun terraces" such as the nose, forehead and chin are particularly affected. In adults, these areas are often used to sunlight, but not in children. This is why headgear is advisable (even for adults) - especially since it not only protects against sun allergies, but also against sunstroke.
Sun allergy: symptoms
The type and severity of sun allergy symptoms vary. Sometimes the symptoms are also delayed, so that it is not so easy for laypeople to identify the sun as the "culprit".
Sun allergy symptoms usually occur when the skin has not been exposed to sunlight for a long time. A sun allergy is therefore particularly common in spring and on a beach holiday.
Polymorphic photodermatosis: symptoms
Polymorphic light dermatosis occurs mainly in the months of March to June. It usually shows up on those parts of the body that are not used to the sun (décolleté, shoulders, neck, extensor sides of the arms and legs). The symptoms can be very different from person to person (hence the addition of the name polymorph = diverse). In addition, they are often delayed. This sun allergy only triggers symptoms hours or days after exposure to the sun:
- The skin begins to itch and burn.
- Reddish spots appear on the skin.
- Blisters, nodules or even blisters develop.
- The affected skin area may swell.
Other forms of sun allergy: symptoms
In addition to polymorphic photodermatosis, there are other types of sun allergy that express themselves somewhat differently. This includes:
Phototoxic reaction
Chemical substances - so-called photosensitizers - make the skin more sensitive to light. Sun allergy symptoms such as itching and an increased tendency to sunburn are the consequences.
Sometimes the phototoxic reaction is triggered by skin contact with photosensitizers (applying perfumes, touching photosensitizing plants, etc.). Photosensitizers (e.g. in medicines or food) can also trigger a sun allergy via the bloodstream or the digestive tract: the skin of those affected then reacts to sun exposure with itching, burning pain or discoloration. Severe sunburn can also occur.
Photoallergic reaction
This rare form of sun allergy is a real light allergy (photo allergy). The immune system forms antibodies, i.e. defensive substances that are directed against a certain substance such as a drug (e.g. antibiotics), cosmetics, make-up or a perfume. The next time it comes into contact with sunlight, the antibodies attack the substance - an allergic reaction occurs. The symptoms of photoallergy are similar to those of the phototoxic reaction. It is therefore often difficult to differentiate between the various forms of sun allergy.
Mallorca acne (acne aestivalis)
This form of sun allergy is also called summer acne. It is considered a special form of polymorphic light dermatosis.
Signs of Mallorca acne are pinhead-sized lumps and patches of skin that itch severely. The nodules resemble acne pustules. In fact, this form of sun allergy is particularly common in people who are prone to acne or oily skin.
Solar urticaria (solar urticaria)
It is rare, but must be taken seriously! Those affected have an abnormal skin reaction to sunlight - itchy wheals form, similar to what happens when you touch a nettle. They disappear again after a few minutes to hours. If larger areas of skin are affected, general symptoms such as nausea or a drop in blood pressure (including dizziness) can occur.
Treatment: sun allergy - what to do?
If you develop symptoms of a sun allergy, try to stay away from sunlight as much as possible.If this is not possible, then you should apply a sunscreen with a sufficiently high sun protection factor (SPF) and cover the skin as much as possible with clothing (long pants, long sleeves, hat).
In the case of photoallergic and phototoxic reactions, you must also avoid the triggering substance.
The symptoms of a sun allergy can be relieved with dairy products (e.g. a quark pack) and - in severe cases - with medication:
Sun allergy treatment with dairy products
If the skin has received too much sun and reacts with a sun allergy, you should cool it and moisturize it. Cooling compresses with buttermilk, quark or yoghurt from the refrigerator do just that. The coolness causes the vessels to contract and any swelling subsides. The moisture helps the damaged skin to recover.
Drug therapy for sun allergies
Medicines are used in severe cases of sun allergy. So-called antihistamines in ointment or tablet form can alleviate the itching, for example in Mallorca acne or light urticaria. Sometimes the doctor also prescribes preparations containing cortisone to suppress the inflammatory reactions of the skin. This may be necessary in the case of a photoallergic reaction, for example.
If general symptoms such as nausea and a drop in blood pressure occur with solar urticaria, you should call a doctor immediately!
Sun allergy: preventive treatment
Sun allergy patients can do a lot to prevent itching, blistering, etc.
Use sufficient sunscreen
The most important thing is that you always take care of adequate sun protection. Of course, this also applies if you are not allergic to the sun! UV rays increase the risk of skin cancer. Use a good sunscreen that has at least a sun protection factor (SPF) of 30. In addition, the product should be as free from preservatives and colorings as possible.
Apply the sunscreen about 30 to 45 minutes before going out in the sun. Then she has enough time to act. How long the protection lasts can be estimated using the following formula: Self-protection factor (approx. 5-45 minutes depending on skin type) x sun protection factor = protected minutes in the sun
With a sun protection factor (SPF) 30 and a light skin type, this would mean: 10 min. X 30 = 300 minutes. To be on the safe side, however, you should only actually spend 60 percent of this calculated time in the sun. By the way: If you sweat heavily or go swimming in between, you should re-apply it.
If you have signs of Mallorca acne, you should only use fat-free sun protection products (such as special gels) and skin care products.
wear clothing
Clothing also protects against the sun's rays, especially if they are made of a material that is not very translucent. For example, hats, scarves and blouses can also partially keep UV rays off the skin on the beach. Manufacturers specify a UV protection factor for some textiles, such as sportswear.
Stay inside
The irradiation is most intense at noon, which is why you should rather stay indoors. Window panes usually block a large part of the harmful rays. Sun allergy patients should possibly apply protective foils.
Phototherapy
In the case of a very strong sun allergy (such as severe polymorphic light dermatosis), phototherapy can be useful. In the spring or some time before a planned vacation trip to the south, the skin is slowly getting used to the sun's rays. To do this, she is exposed to increasing doses of UV light in several sessions. An active ingredient that makes the skin more sensitive to light may be applied beforehand. Then one speaks of photochemotherapy or PUVA (psoralen UV-A phototherapy).
You must never carry out phototherapy on your own - if you make a mistake, extensive skin burns can result! Leave it to a dermatologist to do the job.
Catch free radicals
Some experts are of the opinion that the most common sun allergy (polymorphic light dermatosis) can be caused by free radicals, i.e. reactive oxygen compounds (see "Causes"). They therefore recommend the intake of so-called antioxidants ("radical scavengers") to prevent the symptoms of a sun allergy. These include calcium, omega-3 fatty acids, folic acid, vitamin E and beta-carotene. The effectiveness of antioxidants has not yet been scientifically proven. Nevertheless: Many sufferers report an improvement in their symptoms. Discuss the use of such radical scavengers with your doctor in advance.
Smokers should not take beta-carotene, as it can further increase the risk of lung cancer - which is already increased by the niktoin.
Get help
A sun allergy can affect social life. Some sufferers suffer so much from it that they develop a depressive mood. Then you should ask a doctor for advice. If necessary, professional psychotherapeutic support is useful.
Sun allergy: causes and risk factors
Polymorphic photodermatosis
In the case of polymorphic light dermatosis (PLD), the protective mechanism of the skin against UV rays does not work properly: When sun rays hit the skin, the body normally reacts by increasing the production of melanin. This is a skin pigment that is supposed to protect the genetic material from the damaging UV rays. The skin is colored brown by the melanin. People from southern countries, where the sun shines a lot, therefore generally have a darker skin color. The more often a body is exposed to the sun, the more it usually gets used to the harmful rays.
This is not the case with polymorphic light dermatosis: the skin of those affected is mostly over-sensitive to the UV-A rays in sunlight. Sometimes the UV-B rays or both types of rays are the trigger for this sun allergy. The reason for this is unknown, but there are various possible explanations:
Some scientists believe that the sun's rays produce allergens in the body. Allergens are substances that activate the immune system so that it fights the supposedly harmful substance - just like a conventional allergy. However, this explanatory approach is not yet considered to be secure.
According to another theory, aggressive oxygen compounds (free radicals) form in the skin when exposed to sunlight, which are believed to be the cause of sun allergies. They can damage cells and increase the risk of skin cancer. Damage to skin cells by free radicals could also activate the immune system - resulting in symptoms of polymorphic light dermatosis. However, this assumption has not yet been clearly proven either.
Phototoxic reaction
The phototoxic reaction is triggered by the interaction between UV-A light, human cells and a chemical substance. The latter can be, for example, an active drug ingredient, certain ingredients of perfumes or cosmetics, or plant substances (furocoumarins).
Photoallergic reaction
The photoallergic reaction arises from the fact that the immune system reacts allergically to certain substances under the influence of UV light. As in the case of the phototoxic reaction, these can be ingredients of drugs or cosmetics, for example.
Mallorca acne
Mallorca acne is caused by the interaction of UV-A rays with components of fatty sun cream or the body's own sebum in the top layers of the skin. It has not yet been possible to definitively determine whether the immune system is involved.
Solar urticaria
The exact cause of solar urticaria is unclear. However, it is known that the symptoms are triggered by the UV-A component in sunlight.
Sun allergy: examinations and diagnosis
If you suspect a sun allergy, the doctor will first discuss your medical history with you (anamnesis). For example, he asks about it
- the nature and course of the complaints,
- possible medication intake as well
- possible previous illnesses.
In the vast majority of cases, the sun allergy is a polymorphic light dermatosis. Another form of sun allergy is less common. To confirm the diagnosis, the doctor can do a light test in which he irradiates certain areas of the skin with ultraviolet light. In the case of polymorphic light dermatosis, the typical symptoms appear on the treated areas after a few hours.
If solar urticaria is suspected, the light test must be carried out very carefully: the symptoms, which usually show up within minutes, can be quite severe. Occasionally, there are also severe general symptoms such as a drop in blood pressure, circulatory shock and shortness of breath. Therefore, the test should only be carried out by doctors who are equipped for such emergencies.
In the case of a sun allergy in connection with chemical substances such as the phototoxic reaction, the doctor can apply suspicious triggers (such as components of cosmetics) to suitable skin areas and then irradiate them. This photo patch test can be used to find out which substance is causing the skin symptoms in combination with UV light.
Sun allergy: disease course and prognosis
Unfortunately, there is no cure for a sun allergy. People who are hypersensitive to sunlight experience this problem for a lifetime. However, the symptoms may decrease over time as the skin gets used to the sun.
How severely affected people suffer from the symptoms varies from person to person and depends above all on the type of light allergy. However, through correct behavior, preventive measures and various therapy concepts, severe outbreaks can usually be prevented and the symptoms of a sun allergy significantly alleviated.
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