Sun allergy, whose trigger is sunlight and photosensitive changes on the skin that react to certain medications or care products, especially worsens during the summer.
The effect of light from the UV spectrum can cause changes in the structure of certain skin proteins, which then immune system cells recognize, so an allergic reaction occurs. This is how primary (idiopathic) photodermatoses occur, skin diseases that affect 10-20 percent of the population. These skin reactions are most common during the summer months when the sun’s radiation is strongest.
For patients with this problem, sun protection with a high protection factor is necessary, although sometimes it is not enough, so drug therapy is also applied. There are also secondary photodermatoses that occur as a result of sun exposure and some diseases, contact with certain chemical substances, taking medication … Many drugs can cause photosensitivity reactions, so in the summer months, patients should be additionally warned about this possibility and possibly modify the time of application of these drugs.
What is a sun allergy?
Photoallergic (photosensitive) dermatoses, i.e., sun allergy, are diseases that occur due to increased skin sensitivity to the effects of UV rays. It is most often about autoimmune reactions formed by the cells of the immune system mistakenly recognizing skin cells as antigens after changes in the structure of skin cell proteins caused by UV radiation.
In most people who are allergic to the sun, allergic reactions manifest themselves in the spring if unprotected skin is exposed to the sun.
What is the difference between sunburn and sun allergy?
Although these two problems’ symptoms are similar, the mechanism of occurrence is completely different. In photosensitivity reactions, the patient’s immune system is activated, which leads to the appearance of symptoms even if the person has been in the sun for a relatively short time. On the other hand, burns occur when the body is exposed to UV radiation for so long that it exceeds the skin’s ability to produce melanin, which protects it from the sun’s radiation.
Sun allergy is manifested by the appearance of itching, hives, or burning of the skin, with or without a visible rash, as a reaction to sun exposure. Depending on the type of photosensitivity, the symptoms appear at different speeds, from a few minutes to a few hours after any exposure to the sun, and they also pass.
Are all sun allergies the same?
Idiopathic (primary) photodermatoses are commonly called sun allergies and actually involve different reactions: polymorphic light eruption, actinic prurigo, chronic actinic dermatitis (characteristic of the elderly), solar urticaria.
The polymorphic light eruption is widespread, and according to the latest research, every fourth patient who has a sun allergy has this diagnosis. This type of allergy to the sun often affects young women, and it occurs much less often in men.
Symptoms of this type of sun allergy are manifested in the lower part of the neck, on the back of the hands, on the folds of the legs and arms, a few hours after exposing the skin to the sun’s rays. The polymorphic light eruption is characterized by rash, severe itching, and flushing of the skin, with the appearance of swelling. The swellings resemble insect stings and the inflammation and inflammation that occurs after them. The veil symptoms often disappear after a few days if re-exposure to the sun is prevented and adequate protection is used. Symptoms are present in spring and early summer and decrease as skin exposure to sunlight and strong sunlight decreases. The symptoms decrease as the summer passes but reappear the following year at the same intensity.
Solar urticaria is also a common occurrence of sun allergy. It is very soon after the first exposure of the skin to sunlight. The symptoms are hives, unbearable itching, redness of the skin, very sixth, and flatulence. Solar urticaria is difficult to distinguish from sunburn, but these symptoms quickly disappear as the skin is removed from the sun in less than a day.
Symptoms appear on the lower part of the neck, the back of the hands, the folds of the arms and legs a few hours after exposing the skin to the sun.
What causes a sun allergy?
It is difficult to say why sun allergy occurs. It is assumed that genetics has a certain role because it has been noticed that sun allergies are more common in people who have already had this problem in their family. Risk factors include race, although allergic skin reactions can occur regardless of skin color and amount of pigment, gender (more common in women) and age (polymorphic light eruption more common in 20-35 age groups, chronic actinic prurigo more common in the older adult).
Chemical photosensitivity occurs when various substances are taken into the body or applied to the skin in contact with light. Symptoms similar to these allergies can occur in patients suffering from diseases such as systemic lupus erythematosus (SLE), porphyria, or even side, but also skin diseases such as vitiligo, eczema, rosacea, and the like.
Can some medications cause a reaction on the skin that is similar to that of an allergy?
Various chemicals can cause skin symptoms similar to an allergic reaction in skin and hair hygiene and care products (perfumes, soaps, anti-dandruff shampoos) and numerous medications. These reactions are usually more serious in patients allergic to the sun than in healthy people. A reaction such as contact dermatitis, which occurs when using sunscreen, is not uncommon. It can occur on any part of the skin on which the preparation is applied, but it is most common on those parts that are exposed to the sun.
Drugs that most often cause photosensitivity reactions include retinoids, nonsteroidal anti-inflammatory drugs (ketoprofen, naproxen, piroxicam, ibuprofen), antibiotics (tetracyclines and sulfonamides), antifungals, oral antidiabetics, diuretics, phenothiazines, tricyclics, but also some hormonal preparations for oral contraception. Photosensitivity can occur when the drug is administered orally and applied to the skin. St. John’s wort preparations also often give photosensitive reactions.
How is sun allergy diagnosed?
Since the rash is a nonspecific symptom, sun allergy cannot be diagnosed solely based on rash and redness. However, if the rash occurs only on parts of the skin exposed to the sun, it may be a sign that it may be an allergy. The diagnosis of sun allergy is made mainly after performing specific tests when the skin is exposed to UV light of different wavelengths.
Photo-patch testing is used if the doctor suspects that some photosensitive substances with which the patient came in contact could cause a reaction on the skin. In such tests, two patches impregnated with the substance suspected of causing the reaction are used. The patches are left on the skin for 24 hours, and then the skin under one of the patches is exposed to UV light to see if there are photosensitive reactions.
Are there any recommendations for relieving symptoms?
Beta carotene, the most important form of Vitamin A, is very good for people who suffer from sun allergies and can reduce the skin’s photosensitivity. You should be careful with the use of vitamin A, and you should not overdo it because this vitamin can be toxic.
You should refresh the skin with moisturizing cream and lotions that reduce irritation, peeling, dryness, and itching. Preparations rich in aloe are great for these problems. People who are allergic to the sun should spend as little time in the sun as possible. Exposure time, in particular, should not be increased between ten and sixteen hours. The use of sunscreen is mandatory.
How to best protect yourself from the sun?
Patients who suffer from sun allergies are recommended to wear long-sleeved clothes and legs, preferably one that is not too thin, so that UV rays do not pass through it, and a hat.
All parts of the skin exposed to sunlight, and you should protect those under thin clothing with sunscreen with a high protection factor (SPF 20 or higher). Since there are allergies to UVA, UVB, or both types of UV rays, it is essential to use a product that contains both types of UV filters. You should also protect the skin indoors because UVA rays pass through the glass.
It is important to protect the lips with a suitable contact with a protection factor of at least 20. Patients are recommended gradual sun exposure. You should avoid san-block preparations, with a high content of mechanical filters such as zinc oxide and titanium dioxide, and preparations with para-aminobenzoic acid (PABA) because they can have an additional irritating effect on the skin.
What is the appropriate protection factor for people allergic to the sun and how often should a sunscreen be applied?
People allergic to the sun should not use a protection factor of less than 20, although there are recommendations to use at least a factor of 30. Since UVA rays also cause an allergic reaction, you must indicate the product to have high UVA protection. Sunscreen should be applied to the entire skin area half an hour before sun exposure and then at least once every two hours.
Although the product is waterproof, you should apply it every time after swimming and after each towel wiping. Water resistance, namely, depends on the time spent in the water, and the products that are so declared imply protection for 40 minutes, which includes the time required to dry the skin without rubbing with a towel.
What to do if a rash appears?
If a rash appears when a person is exposed to the sun, especially if it is happening for the first time, it should be treated as a burn. It is best to put on a cold compress and soothe any pain with paracetamol. You should then seek a doctor’s advice, who will see if it is just a burn or a photosensitive reaction of the primary or secondary type.
When is drug therapy recommended?
Itching is a basic symptom complained of by patients who have a problem with photosensitive skin reactions. If the patient does not tolerate itching, the use of oral antihistamines (loratadine, cetirizine, desloratadine, levocetirizine) is recommended. In more severe forms, corticosteroid preparations for topical use can also be used, most often with hydrocortisone or triamcinolone.
Some cases may require the oral use of corticosteroids, such as prednisone. It is generally short to minimize side effects. It is indicated before prolonged exposure to the sun, for example, before summer vacations or trips to the tropics, in people with severe allergies.
It is also possible to do phototherapy – desensitization of the skin with repeated exposure to light. It is usually recommended for patients with solar urticaria or polymorphic light eruption. It is performed under the supervision of a doctor, usually five times a week for three weeks, to induce tolerance and alleviate symptoms.
What is a protective factor?
Sun protection factor (SPF) is a measure of protection against UVB radiation. The ratio between the dose of UV radiation leads to erythema’s appearance in protected skin and the radiation dose that leads to the same phenomenon in unprotected skin. SPF 2 can absorb about 50 percent of the received radiation, while SPF 45 absorbs 98 percent of UVB radiation. According to the European Union directive, in order not to confuse the users, the biggest factor that you can find on cosmetics on the European market is 50+.
You should bear in mind that the degree of protection does not increase linearly with SPF growth. It is important to note that laboratory tests that determine the SPF involve applying 2 mg / cm2 of a protective agent, which means that a standard 200 ml bottle is used for about four to five smears of the whole body. Patients usually apply four times less protection (0.5 mg / cm2), so you should bear in mind that this significantly reduces the stated protection factor.
To prevent photoallergic eruption caused by sunlight and application to the skin body cream, perfumes, lotions, make-up … Dermatologists advise you not to use these products when exposed to the sun because the chemicals that these products contain can also cause allergies.
The causes can be some medications, primarily antibiotics and birth control pills. Even sunscreens can cause side effects on the skin, so you should test them – apply a small amount, preferably on the forearm, and wait a while to see if the skin will react or not.
Sounds amazing, but artificial sweeteners, lettuce, carrots, celery, figs, primrose, parsnips, and dill can be the cause, so it is advisable to avoid these foods during sun exposure.
Preventive measures are gradual adjustment of the skin to the sun, application of UV protection cream with a high factor, and adequate clothing – best in white, long sleeves and socks, and a hat, cap … something that covers the face enough.
Doctors say yes, sun allergy is not dangerous to health, but if you notice any more violent reactions on the skin, consult a dermatologist.