Under the influence of ultraviolet (UVA) radiation, substances of external origin that are present in the skin become photoactivated, as well as sometimes their own metabolites created as a result of diseases. These substances are, first and foremost, some of the components of the medicines that we use orally, cosmetics that we apply to the skin, some herbal and plant substances. These types of photoactive substances - giving light energy to the tissues of our body - simultaneously release toxic free radicals. This causes damage to the skin cells and acute inflammation. This is manifested by skin lesions and lesions - mainly erythema and edema and urticaria, blisters, eczema, etc. This reaction is usually limited to the place where both these factors simultaneously act - i.e., light radiation and the presence of a phototoxic substance.
Drug-induced urticaria caused by ultraviolet (UV) radiation may appear in the exposed areas - on the face, neck, and forearms. In the visible case, severe erythema occurred, combined with edema. Symptoms were accompanied by severe pruritus and burning. The symptoms lasted for several days. A specialist doctor, who was notified by a patient concerned about the severity of symptoms and their chronicity - said photodermatosis.
Phototoxic reactions - allergy to sunlight
The mechanism of sensitization to sunlight is as follows - under the influence of light energy present in the body the aforementioned photoactive molecules - chemical compounds from foods, drugs, cosmetics, as well as own toxic metabolites formed during some diseases - are transformed into allergens! These are quite new substances that arise from the above-mentioned chemical compounds that combine into stable complexes with skin cell proteins. These new complex compounds already contain a sensitizing protein particle, are alien to the body and are therefore treated as allergens. The longer or shorter solar exposure will now be sustained to trigger a defensive reaction of the immune system that confuses photoallergic reactions with germs. The result is acute local inflammation of the skin that causes urticaria, swelling and other skin symptoms.
Where are the most common skin lesions under the influence of the sun?
Skin changes are usually limited to exposed sites, and therefore - face, neck, cleavage, hands, shins. But be careful! The sun's rays can also penetrate through clothing.
So what is the "sun" allergy?
Allergy - it is, to a large extent, a fixation of the phototoxic reaction. Chemically modified photoactive compounds - most often drugs and cosmetics - the body perceives as allergen-dangerous for health. Therefore, it constantly produces renewable antibodies to control them, resulting in an allergic reaction that becomes faster and more reproducible.
Jare there symptoms of light allergy?
Photoalgic reactions can be urticaria - there are blisters, like after burning a nettle. Urticaria may be combined with swelling, pruritus and skin burning. However, the symptoms more often resemble the so-called contact eczema - visible as redness, with the presence of lumps, sometimes oozing. It may be accompanied by pruritus.
How fast do you experience allergies after sunbathing?
A certain incubation time is required for the emergence of urticaria and other symptoms. The reaction usually occurs within 24 - 48 hours of body exposure to the sun. Symptoms of allergies may appear in a place distant from the action of a given factor.
What drugs threaten sun sensitization?
The most frequently mentioned are: sulfonamides (eg Biseptol), sulfonamide antidiabetic agents (Diabetol, Chloropropamide), some diuretics and sedatives. If you use this type of medication, you should check with your doctor whether or not they cause allergies.
And cosmetics?
With photoallergenic cosmetic raw materials - used for example for creams, ointments and aromatherapy massages - should be mentioned some essential oils, such as bergamut (also added to perfumes), oil from St. John's wort or from angelica. Photoallergising may also be drinking herbal infusions of these herbs.
Is allergic allergy to light alone possible?
Yes, it should be taken into account that photoallergic reactions may leave photosensitivity - i.e. cause changes due to radiation itself. Such a situation applies to, for example, people with systemic lupus or lupus erythematosus (diseases genetically conditioned as a result of which the body itself develops phototoxic substances, e.g. porphyrin). It also affects people suffering from a lack of melanin synthesis - a dye that gives the skin brown tan color, ie those suffering from phenylketonuria and congenital vitiligo.
Do sunscreens protect against allergy to UV rays?
Yes, strong, modern preparations in the form of protective creams with a full spectrum of protection protect against both UVB and UVA radiation. The prophylactic use of this type of preparations, especially containing zinc oxide, may reduce eg the risk of skin discoloration. It was also shown that they not only prevent skin changes, but also can regenerate damage. Physicians' experience shows that protective filters are helpful, especially after drug withdrawal.
What else should be done to prevent sun allergies?
The most important task of the patient is to check the information leaflet of the medicine (or medicinal product) - the so-called interaction and side effects. You should also ask your doctor about the same. Unfortunately, not all patients do it. It is obvious that once we know about the threat from the sun - we should avoid strong irradiation in the warm season of the year. How to do it? Avoid exposing the exposed body to the sun and walking and doing things in the summer around noon - that is, 11 - 15. In addition, a sunshade and a hat with a large brim are helpful. Preserving the precautions will help avoid unnecessary suffering. Of course, if we take the aforementioned medicines or use cosmetics - we give up the solarium and mountain sun in winter.
Ed. Edward Ozga Michalski, MA
Consultation by prof. dr hab. med. Andrzej Danysz
