Margarita Hecht,
Leading Dermatologist of the Children-Butterfly Foundation
Sun allergy is the immune system's response to ultraviolet light. Under its influence, the skin changes, and the immune system recognizes the altered cells as foreign [1].
All About Sun Allergy:
- Emergence
- Views
- What does it look like
- Causes
- Prevention
- Treatment
- Differences from prickly heat
What happens in the body with sun allergies?
In scientific terms, when exposed to sunlight, a substance called histamine is released. It is produced by cells in the skin and internal organs in response to contact with an allergen, a foreign object that irritates the skin. This mechanism is called antigen-antibody.
To explain metaphorically, an antibody is a skin cell that can be compared to a metal, in turn, an antigen is an allergen, it is like a magnet. The metal attracts the magnet, and as a result, an antigen-antibody complex is formed, and due to this interaction, histamine is released. And the result of this process we see on the skin rash, itching and other manifestations of allergies.
Which parts of the body are most affected by sun allergies?
An allergic reaction to the sun can occur anywhere on the body, but most often it occurs on parts that are actively exposed to the sun: arms, legs, hands, back and front of the neck, chest.
Who can get sun allergies?
Allergy symptoms are common in those who are particularly sensitive to the sun. For some, this is a hereditary reaction. Others develop allergic symptoms under the influence of additional factors, such as drugs or certain plants that come into contact with the skin.
What to do if you are allergic to the sun?
Mild cases of sun allergy usually resolve without treatment. In severe cases, the affected areas are treated with steroid creams or pills prescribed by a doctor. People with severe sun allergies will need to take preventive measures and wear sunscreen clothing.
What types of sun allergies are there?
There are several types of sun allergies.
- Actinic prurigo is an inherited version of the sun allergy that affects all races. Symptoms are stronger than other types and may begin as early as childhood.
- Photoallergic reaction, or photodermatitis, is a type of allergic reaction that occurs when a chemical (cream, cleanser, perfume) applied to the skin reacts with sunlight. Symptoms sometimes do not appear for two to three days.
- Polymorphic light eruptions(PMLE-polymorphic light eruption), or polymorphic photodermatosis, solar pruritus, polymorphic photodermatitis. This is the most common form of sun allergy. 10 to 15% of the population suffer from this disease. It is more common in women than in men and usually begins in adolescence and 20 years of age. Polymorphic rashes are a rash with different elements: blisters, reddened areas, spots, vesicles, papules. The skin in the affected area is very itchy. Most cases occur in spring and summer. Such rashes most often appear in those places that are hidden under clothes in the cold season, and are open in summer. First of all, this is the chest area and the front of the neck. Symptoms usually appear several hours after sun exposure. People with polymorphic light rash are at high risk of being deficient in vitamin D because the body needs a certain amount of sun exposure to produce it.
- True solar urticaria is an allergic reaction to the sun that is relatively rare and causes the classic manifestations of urticaria [2]. A pathological reaction can begin after just a few minutes in the sun. Mostly young women suffer from this. Symptoms can be mild or severe and can include anaphylactic shock, a life-threatening allergic reaction that requires urgent medical attention.
What does sun allergy look like?
The affected skin looks different depending on what caused the allergy. But all types of reactions have similar symptoms:
- redness;
- itching or pain;
- elements of small diameter, rising above the level of the skin, which can merge with each other;
- peeling and crusting;
- isolated blisters or spilled hives.
Symptoms occur only on an area of skin that has been exposed to the sun and usually develop within minutes or hours.
Actinic prurigo usually presents as severely itchy, crusty papules, elements that rise above the surface of the skin.
A burning or itchy rash, blisters, or fluid-filled blisters are common with PMLE and photoallergic reactions. The rash goes away within two hours of sun exposure. Chills, headache, nausea, and malaise can last one to two hours.
Solar urticaria occurs in minutes. First, there is a burning sensation and only then a characteristic rash that lasts from several days to several weeks. In some cases, the skin may darken, but this symptom disappears within 30 minutes or two hours. But as soon as the skin is exposed to the sun again, the allergy symptoms return.
When should you see a doctor?
If you have unusual, disturbing skin reactions after exposure to sunlight, this is a good reason to see your doctor. For severe or persistent symptoms, it is best to see a dermatologist, a doctor who specializes in diagnosing and treating skin conditions [3].
What are the risk factors?
- Blood relatives with sun allergies. You are more likely to get sun allergies if your brother or mother has the same condition.
- A specific phototype is skin color and its ability to respond to UV radiation from the sun. The phototype is genetically predetermined and does not change during life. Although any person can develop an allergy to the sun, people with fair skin, phototypes 1-3, are more susceptible to it [4].
Causes of sun allergies
The fact why some people are allergic to the sun, while others do not, is still being studied by doctors.
Some allergy symptoms occur when a person ingests certain substances or applies them to the skin and then spends a lot of time in the sun. These "catalysts" for allergies include:
- flavors;
- disinfectants;
- some of the chemicals used in sunscreens;
- cosmetic preparations;
- medicines (tetracycline antibiotics, sulfa drugs, fluoroquinolones, NSAID pain relievers based on a propionic acid derivative, ibuprofen and sodium naproxen, as well as diuretics for high blood pressure and heart failure);
- household chemicals.
If you've ever touched lime or certain plants and then exposed your hand to the sun, you may have experienced phytophotodermatitis [5]. The skin begins to burn and a rash appears (the same can happen after cooking celery or parsley, if you then immediately go out into the sun). Artificial sweeteners, including calcium cyclamate or sodium cyclohexyl sulfamate, can also promote photosensitivity, along with the popular herbal remedies St. John's wort and ginkgo biloba.
How is sun allergy diagnosed?
The attending physician examines the skin and takes a medical and family history to make a diagnosis. In some cases, the doctor may recommend a blood test or phototesting - a diagnostic method in which a small area of the skin is exposed to a measured amount of ultraviolet radiation. If symptoms appear on the treated skin area, the test is considered positive and confirms that the skin rash is associated with the sun. Sometimes a skin biopsy is required to make a diagnosis.
All of these methods not only confirm or deny sun allergies, but also eliminate other skin problems, such as eczema and lupus.
Sun allergy prevention
During the hours of maximum solar activity, between 10 am and 4 pm, try to stay in the shade
- Use a sunscreen with a broad spectrum SPF of 30 or higher (with UVA and UVB protection) and is waterproof.
- Apply a cream based on aloe, centella asiatica, azulene, dexpanthenol juice to the already affected skin areas daily - these products moisturize, restore the epidermal barrier and reduce burning. Locally - that is, on the affected areas - you can use blockers of H-1 histamine receptors: diphenhydramine, chloropyramine, cetirizine, levorotatory isomer of cetirizine, desloratadine.
- Wear sunglasses and clothing that covers your body as much as possible: long-sleeved shirts and wide-brimmed hats will protect your skin from sun exposure.
- Avoid fine fabrics with loose weaves - UV rays can pass through them.
- Do not forget about special areas - around the eyes, lips and ears. Protective cream must be applied to them as well. Choose a product designed specifically for special areas with an SPF of 30 or higher.
- Wear sunglasses with UV protection.
- Carotenoids, such as β-carotene, found in carrots, provide UV protection. These compounds are absorbed into the skin after being digested. People with high levels of carotenoids in their skin are less susceptible to sunburn. However, consuming a lot of carotenoids can change your skin color.
How to treat sun allergies?
For therapy, you can try an over-the-counter antihistamine, such as diphenhydramine or chlorpheniramine as the active ingredient. They are both sold under several brand names and are used to relieve itching. A cream containing hydrocortisone will also work.
If symptoms are severe, a doctor should be consulted, who will suggest an oral antihistamine [6] or a strong prescription corticosteroid cream.
How is sun allergy different from prickly heat?
Miliaria occurs when pores become clogged and sweat collects under clothing or under blankets. The main difference is that prickly heat can appear without exposure to sunlight. In hot and humid weather, a heat rash can appear on any part of the body, especially in the folds of the skin. Most often, prickly heat appears under the breast, in the groin, in the armpit folds and on the inner thighs.
Prickly heat can be found at any time of the year. In babies, it happens when they are wrapped in blankets or dressed too warmly. Miliaria clears up on its own after a few days, while solar urticaria usually lasts only a few hours.
# instruction: how to choose the right sunscreen.