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Sun allergy: description, triggers, symptoms, treatment

by Josephine Andrews
Published: Last Updated on 215 views

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, causing symptoms such as itchy skin, burning, blisters or wheals. Read what triggers a sun allergy and how it can be alleviated or even avoided!

ICD codes for this disease:

ICD codes are internationally valid codes for medical diagnoses. They can be found, for example, in doctor’s letters or on certificates of incapacity for work.


quick overview

  • What is sun allergy? Usually not a real allergy, but another type of hypersensitivity to UV radiation
  • Causes: not finally clarified; Allergens or free radicals (aggressive oxygen compounds) are suspected
  • Symptoms: variable: itching, reddening of the skin, blisters and/or blisters are common
  • Diagnostics: patient consultation, light test
  • Treatment: cool, moisturize, in severe cases possibly medication or getting used to it by pre-radiation by the doctor
  • Prognosis: Over time, the skin gets used to the sun, so the symptoms gradually decrease. However, those affected by a sun allergy never get rid of it completely.

Sun allergy: description

Typical symptoms of sun allergy 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, ie an overreaction of the immune system (exception: photoallergic reaction). Instead, the body of those affected can no longer adequately protect itself from the sun’s rays.

Normally, the body reacts to sunlight by increasing the production of skin pigments: This so-called melanin makes the skin look brown and protects the genetic material in the cells from the damaging 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, the formation of blisters or blisters or reddening of the skin.

With a share of over 90 percent, polymorphic light eruption (PLD) is by far the most common form of sun allergy. In Western Europe, about 10 to 20 percent of the population suffer from it. Young, fair-skinned women are particularly affected. Many children also suffer from PLD.

Sun allergy in children

Some children also suffer from sun allergies. Toddlers and babies should generally be sunscreened with 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 sun allergies more quickly.

The latter is the most common on the face. The so-called “sun terraces” such as the nose , forehead and chin are particularly affected . In adults, these areas are often already used to the sun’s rays, but in children they are not. It is therefore advisable to wear a hat (even for adults) – especially since it not only protects against sun allergies, but also against sunstroke .

Sun allergy: symptoms

The nature and severity of sun allergy symptoms vary. Sometimes the symptoms also appear with a delay, so that it is not so easy for laypeople to identify the sun as the “culprit”.

Sun allergy symptoms usually appear when the skin has not been exposed to the sun for a long time. Sun allergies are particularly common in spring and on beach holidays.

Polymorphic light eruption: symptoms

Polymorphic light eruption occurs mainly in the months of March to June. It usually appears 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 vary greatly from person to person (hence the suffix polymorph = multifaceted). 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 form.
  • The affected area of ​​skin may swell.
Sun allergy – commonly affected skin areas
In the case of sun allergies, certain substances make the skin particularly sensitive to UV rays. It manifests itself in skin reddening, itching and often blistering.

Other forms of sun allergy: symptoms

In addition to polymorphic light eruption, there are other types of sun allergy that manifest themselves in different ways. This includes:

Phototoxic reaction

Chemical substances – so-called photosensitizers – make the skin more sensitive to light. The consequences are sun allergy symptoms such as itching and an increased tendency to sunburn.

Sometimes the phototoxic reaction is triggered by skin contact with photosensitizers (applying perfumes, touching photosensitizing plants, etc.). But photosensitizers (eg 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 (photoallergy). The immune system forms antibodies, ie defensive substances, which are directed against a specific substance such as a drug (eg antibiotics), cosmetics, make-up or perfume. The next time they come into contact with sunlight, the antibodies attack the substance, resulting in an allergic reaction. 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 eruption.

Signs of Mallorca acne are pinpoint lumps and patches of skin that itch intensely. The nodules resemble acne pustules. In fact, this form of sun allergy is particularly common in people who are prone to acne or have oily skin.

Solar urticaria (urticaria solaris)

It is rare, but must be taken seriously! In those affected, the skin reacts abnormally to sunlight – itchy bumps appear, similar to those that appear after touching a nettle . After a few minutes to hours they disappear again. If larger areas of skin are affected, general symptoms such as nausea or a drop in blood pressure (including dizziness) can also occur.

Treatment: sun allergy – what to do?

If you develop symptoms of sun allergy, you should stay away from sunlight as much as possible . If this is not possible, then you should apply sunscreen with a sufficiently high sun protection factor (SPF) and also cover your skin with clothing as much as possible (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 been exposed to excessive sun exposure and is reacting with a sun allergy, you should cool and moisturize it. Cooling compresses with buttermilk, quark or yoghurt from the fridge do just that. The coolness causes the blood vessels to contract and any swelling to subside. The moisture helps damaged skin to recover.

Drug therapy for sun allergy

Medications 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 solar urticaria. Sometimes the doctor also prescribes preparations containing cortisone to stop the inflammatory reactions of the skin. This may be necessary, for example, in the event of a photoallergic reaction.

If general symptoms such as nausea and drop in blood pressure occur with solar urticaria, you should contact a doctor immediately!

Sun allergy: preventive treatment

Sun allergy patients can do a lot to prevent itching, blistering, etc. from occurring in the first place:

Use enough sunscreen

The most important thing is that you always pay attention to sufficient 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 offers at least a sun protection factor (SPF) of 30. In addition, the product should be as free as possible from preservatives and colorings.

Apply 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 (depending on skin type approx. 5-45 minutes) x sun protection factor = protected minutes in the sun

With a sun protection factor (SPF) of 30 and a light skin type, this would mean: 10 minutes x 30 = 300 minutes. To be on the safe side, however, you should only actually spend 60 percent of this calculated period in the sun. By the way: If you sweat heavily or go swimming in between, you should apply cream afterwards.

If there are signs of Mallorca acne, you should only use oil-free sun protection products (eg special gels) and skin care products.

wear clothing

Clothing also protects against the sun’s rays, especially if it is made of a material that is not very translucent. For example, hats, towels and blouses can partially block UV rays from the skin on the beach. For some textiles, manufacturers specify a UV protection factor, such as sportswear.

stay inside

The radiation is most intense at midday, which is why you should stay indoors then. Window panes usually keep out most of the harmful rays. Sun allergy patients should possibly attach protective films.


In the case of very severe sun allergy (eg severe polymorphic light eruption), phototherapy can be useful. Here, in spring or some time before a planned vacation trip to the south, the skin is already slowly getting used to the sun’s rays. For this purpose, she is irradiated with 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 should never carry out phototherapy yourself – mistakes can result in extensive skin burns! Leave it to a dermatologist to do it.

Catch free radicals

Some experts are of the opinion that the most common sun allergy (polymorphic light eruption) can be caused by free radicals , ie reactive oxygen compounds (see “Causes”). They therefore recommend taking 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 symptoms. Discuss the intake 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 nicotine.

get help

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 light eruption

In the case of polymorphic light eruption (PLD), the skin’s protective mechanism against UV rays does not work properly: when the sun’s rays hit the skin, the body normally reacts by producing more melanin. This is a skin pigment that is supposed to protect the genetic material from damaging UV rays. The skin turns brown due to the melanin. People from southern countries, where the sun shines a lot, therefore generally have a darker skin color. Usually, the more a body is exposed to the sun, the more it becomes accustomed to the harmful rays.

This is not the case with polymorphic light eruptions: the skin of those affected is usually overly sensitive to the UV-A rays in sunlight. Sometimes the UV-B rays or both types of rays are the trigger of this sun allergy. The reason for this is unknown, but there are various possible explanations:

Some scientists believe that allergens are formed in the body as a result of the sun’s rays. Allergens are substances that activate the immune system so that it fights the supposedly harmful substance – like with a conventional allergy. However, this explanation has not yet been taken for granted.

According to another theory, aggressive oxygen compounds (free radicals) form in the skin when exposed to sunlight, which are said to be the cause of sun allergy. They can damage cells and increase the risk of skin cancer. The damage to skin cells by free radicals could also activate the immune system – resulting in symptoms of polymorphic light eruption. However, this assumption has not yet been unequivocally proven.

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 ingredient in a drug, certain ingredients in perfumes or cosmetics, or plant substances (furocoumarins).

photoallergic reaction

The photoallergic reaction occurs when the immune system reacts allergically to certain substances under the influence of UV light. As with the phototoxic reaction, these can be ingredients in medicines or cosmetics, for example.

Majorca acne

Mallorca acne is caused by the interaction of UV-A rays with components of fatty sunscreen or the body’s own sebum in the upper layers of the skin. So far, it has not been possible to definitely 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: investigations and diagnosis

If a sun allergy is suspected, the doctor will first talk to you about your medical history (anamnesis). For example, he asks about

  • the type and course of the complaints,
  • a possible intake of medication as well as
  • possible previous illnesses.

In the vast majority of cases, the sun allergy is a polymorphic light eruption. Rarely is another form of sun allergy behind it. 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 eruption, the typical symptoms appear after a few hours on the treated areas.

If solar urticaria is suspected, the light test must be carried out very carefully: the symptoms, which usually appear 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 performed by doctors who are prepared for such emergencies.

In the case of a sun allergy in connection with chemical substances such as the phototoxic reaction, the doctor can apply suspected triggers (such as ingredients in 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: course of the disease and prognosis

Unfortunately, sun allergies cannot be cured. This problem accompanies people who are hypersensitive to sunlight for the rest of their lives. However, symptoms may diminish over time as the skin adjusts to the sun.

The extent to which those affected suffer from the symptoms varies from person to person and depends above all on the form of the light allergy. Proper behavior, preventive measures and various therapy concepts can usually prevent severe outbreaks and significantly alleviate the symptoms of a sun allergy.

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