Some people cannot tolerate sunlight - when their skin comes into contact with sunlight, it sooner or later develops symptoms such as an itchy rash, hives, or blisters. This is often referred to as a sun allergy .
However, the symptoms are not caused by an allergy. In most cases, they are caused by the skin condition polymorphic light eruption (PLE) .
This condition generally first appears in affected individuals every year at the beginning of spring, when the sun shines for longer again and its rays become stronger.
This article discusses sun allergy, related conditions such as phototoxic reactions, possible causes, and ways to protect against and treat it. With one click, you can select the section you would like to read and jump directly to it.
Contents
- What symptoms are typical of a “sun allergy”?
- What causes polymorphic light eruption?
- What are phototoxic and photoallergic reactions?
- How can you protect yourself if you have a sun allergy?
- Can PLE be cured?
What symptoms are typical of a “sun allergy”?
For most affected individuals, sun allergy symptoms first appear in spring on areas of skin that had not been exposed to sunlight for a long time. The effects are therefore mainly observed on the arms and legs, as well as on areas of the torso or cleavage.
In people with more pronounced polymorphic light eruption, increasingly intense sunlight also causes reactions on the face. Only in very severe cases of PLE do affected individuals experience skin reactions in winter as well. In general, the condition occurs more frequently in people with fair skin . It should also be noted that symptoms usually begin only one or two days after the skin’s first contact with sunlight.
Typical symptoms of PLE include skin redness, rash, and small blisters. The affected areas often cause severe itching. In severe cases, pustules and bleeding areas may even develop - scratching the itchy areas should be avoided at all costs.
If noticeable warmth in the affected areas accompanies the symptoms, this also indicates a sun allergy. If reddened blisters form that look similar to hives caused by stinging nettles, this could be solar urticaria . This is a rare form of sun allergy that can also affect the circulatory system.
If circulatory problems such as dizziness, nausea, or weakness occur along with the symptoms, medical help should be sought immediately. A sun allergy is generally more bothersome than dangerous, and severe cases are rare.
However, other dangers such as sunburn or heatstroke caused by overheating can also occur while spending time in the sun. If sun allergy symptoms occur at the same time as sunburn, they could be overlooked.
Very severe sunburn is often accompanied by overheating of the body, which can lead to heat collapse. Fortunately, polymorphic light eruption itself does not cause such problems.
What causes polymorphic light eruption?
Human skin has a mechanism that enables it to react to increasing or more intense exposure to UV light. It produces increased amounts of melanin - a pigment that darkens the skin and blocks UV light. Melanin is why the skin tans after sunbathing.
In polymorphic light eruption, this process appears to be impaired. It is therefore not surprising that people with fair skin types are particularly affected by sun allergy. Their skin stores less melanin than darker skin types and is also more sensitive to sunburn. It is a well-known phenomenon that many pale-skinned people do not tan, or tan only with difficulty, in summer.
Exactly how PLE develops has not yet been clarified - in addition to its connection with melanin, several other theories are circulating. For example, it is suspected that UV light stimulates the production of free radicals in the skin cells of people with a “sun allergy.”
These are thought to cause an overreaction of the skin’s immune system. Another theory suggests that exposure to sunlight can produce allergens that trigger PLE like a classic allergy. None of these theories has yet been proven.
What is Mallorca acne?
The so-called “Mallorca acne” (acne aestivalis) was a skin condition that was particularly widespread among holidaymakers in sunny travel destinations during the 1980s. At that time, Mallorca was becoming the Germans’ favorite island and recorded particularly many cases - hence the name. The symptoms resemble those of a sun allergy and can progress to the formation of acne-like pustules.
Today, however, this condition is hardly seen anymore, because it turned out that acne aestivalis occurred only in connection with certain sunscreens and in interaction with UV radiation. The responsible ingredients were identified and are no longer included in modern products. Whether Mallorca acne was actually an immune reaction or “just” skin irritation remains unclear.
What are phototoxic and photoallergic reactions?
Photoreactions can occur in connection with various substances. Some perfumes, for example, may contain ingredients that change when exposed to sunlight and develop toxic or skin-damaging properties. In addition, there are various plant species considered “phototoxic” that cause symptoms resembling a sun allergy.
Phototoxic reactions are caused by the “poisoning” of skin cells by biological or chemical substances in combination with UV exposure. Various medications can increase the skin’s sensitivity to light. Both medications for external use (creams, ointments, etc.) and oral preparations (some anti-rheumatic drugs, diuretics, etc.) may have these properties.
If known, this is listed among the medication’s side effects. Anyone taking such a medication must avoid UV light, as otherwise skin irritation or even skin damage can occur very quickly. The risk of developing sunburn therefore increases significantly.
Phototoxic reactions are also often caused by plants whose sap contains phototoxic furocoumarins. These substances are found, among other things, in the peel of citrus fruits .
Another prominent example is St. John’s wort, which contains high concentrations of hypericin. Hypericin is used, for example, as an active ingredient in antidepressants. However, it increases the skin’s sensitivity to UV light, because phototoxic substances only become toxic when they come into contact with UV light.
Gardeners and landscapers come into contact with phototoxic plants particularly often. However, symptoms sometimes also appear after a walk in short clothing through flowering meadows.
The resulting skin problems are commonly referred to as “meadow grass dermatitis” , as they are triggered by various garden or wild plants. Well-known phototoxic plants include bishop’s weed, spotted hemlock, herbs such as anise, dill, fennel, or coriander, and umbellifers such as giant hogweed.
Photoallergic reactions are triggered by the interaction of UV light with chemical or other substances. Some medications, perfumes, or cosmetics can provoke immune system overreactions in affected individuals. Mallorca acne may have been a photoallergic reaction.
How can you protect yourself if you have a sun allergy?
The simplest way to prevent a sun allergy is to avoid sunlight. This does not mean that people with PLE can no longer leave the house. Unless you have a severe form, you can effectively protect yourself with long clothing and sun hats to expose as little skin as possible to the sun.
Combine your choice of clothing with a high-quality sunscreen. It is advisable to choose a cream with the highest possible sun protection factor and a combination of UVA and UVB filters.
Anyone who is sensitive to heat and has photosensitive skin should gradually get used to the sun and heat. Initially, expose yourself to the sun for only a few minutes a day. In many cases, sun allergy symptoms subside once the skin has become accustomed to UV light. Sunlight is strongest around midday - preferably leave the house in the morning or toward evening.
It is sometimes said that dietary supplements containing antioxidants such as vitamin E or beta-carotene make the skin less sensitive to UV light. However, this is only a theory - their effectiveness against sun allergy has not been scientifically proven.
If you suffer from a severe form of polymorphic light eruption, you should definitely seek medical help.
Can PLE be cured?
Polymorphic light eruption can be treated - it cannot be completely cured. Nevertheless, even in many severe cases that prevent natural acclimatization to sunlight, a form of desensitization can be carried out under medical supervision.
To do this, contact a dermatology practice near you. There, targeted light therapy can be performed to gradually and gently acclimatize the skin to UV radiation. If a severe sun allergy is known, this treatment can begin during the winter months to prepare the skin for spring and summer.
Itching, rash, and blister formation can be treated with cooling and soothing ointments. In severe cases, corticosteroid-containing medications can provide relief. However, treatment and management of sun allergy should aim to prevent an acute outbreak from occurring in the first place.
