Basics
What is meant by "sun allergy"?
There are a number of diseases that can lead to enormous itching, blistering and swelling of the skin when exposed to the sun. However, this symptomatology which is generally referred to as "sun allergy" does not always refer to diseases which are actually based on an allergic reaction:
- Polymorphous light dermatosis (PLD)
- Majorca acne
- Photoallergic reactions
Polymorphous light dermatosis (PLD)
This disease is overwhelmingly responsible for a "sun allergy". It is characterized by itchy skin areas as well as swelling and blistering of the skin. It usually affects areas of the skin that are rarely exposed to direct sunlight, such as the shoulders, the extensor sides of the limbs or the décolleté.
Women, especially those with fair skin types, are overwhelmingly at risk for polymorphous light dermatosis. Unfortunately, the occurrence of PLD is difficult to predict because the course of this disease can be very variable. In the majority of cases, the symptoms disappear after about one to three weeks if the affected person stays away from direct sunlight.
It is considered clear that sunlight is responsible for the disease, but it is not yet known exactly how sunlight leads to skin damage. Due to the effect of high-energy solar radiation, very reactive oxygen radicals can be formed, which are rendered harmless in the intact skin in various ways. It is assumed that in polymorphous light dermatosis the neutralization of these oxygen radicals is insufficient and that this leads to skin damage and the symptoms described.
Protect against skin damage
In order to protect the skin from polymorphous light dermatosis, it is essential to use sun creams with a high UVA protection factor, such as those containing the UV absorber Mexoryl. Also the use of sun creams with added antioxidants like glycosilrutin, vitamin C or E may be useful. Furthermore, it is recommended to apply such sun protection products about two weeks before a planned vacation in order to prepare the skin even better for the sun radiation.
Although some patients use calcium preparations to counteract polymorphous skin dermatosis, no positive effect of these preparations has yet been scientifically established. On the other hand, the consumption of omega-3 fatty acids from fish oil has been shown to have a positive effect on the disease.
In very severe forms of the disease, there is also the possibility of light therapy, in which the patient's skin is gradually accustomed to light.
Prevention
Although there is no proven evidence for a preventive effect of the oxygen radical scavenger beta-carotene, its intake is recommended in many cases. However, smokers are not advised to take beta-carotene because it can increase the risk of lung cancer. In case of uncertainties the intake should be discussed with a doctor in any case.
Mallorca acne
Majorca acne is caused by the interaction of oxygen radicals which have been formed under UV radiation and fatty substances from sun creams or from the sebum of the own skin. The reaction of the radicals with the fats causes damage and inflammation of the skin in the area of the hair follicles. This usually manifests itself in the form of acne, especially in the neckline. Especially teenagers with oily skin and known acne problems tend to develop Mallorca acne.
In order to protect oneself from Mallorca acne, one should use gel-based sun protection products with a high UVA protection factor. Gels hardly contain any greasy ingredients but cause tension of the skin. It should be mentioned that the label "hypoallergenic" on sun protection products does not mean that these creams protect against Mallorca acne, but that allergic reactions to the substances contained are rarely developed. In order to counteract the development of Mallorca acne, one should therefore pay attention to labels such as "gel" or "fat-free" and avoid creams and care products containing fat during the stay in the sun.
Photoallergic reactions
There are substances that are altered by exposure to the sun in such a way that they can cause allergic reactions and skin changes.
There are a number of medications (antibiotics, painkillers, diuretics) that can cause photoallergic reactions in this way. But also some herbal substances (parsley, lemons, celery) can cause this form of sun allergy. Furthermore, there are also some care products or perfumes that can damage the skin in this way.
In any case, one should always find out if a photoallergic reaction can develop when taking a medication. People who suffer from intolerances to chemical light protection products should use preparations with mineral filters (so-called micropigments, Lavidal®). Due to the increasing demand for these products, the supply of sunscreens with mineral filters has grown considerably in recent years.
Immediate help
If an allergic reaction has already occurred, the symptoms can be treated with antihistamines. These have the advantage of a quick onset of action with a weakened effect. Another option is the use of over-the-counter cortisone gels. These preparations usually have a stronger effect, but the onset of action is delayed. There are now a number of cortisone products that are well tolerated when used for a short time.
