Sun allergy is a condition in which the sun causes skin reaction. For most people, symptoms include itching and red rash in areas that were exposed to the sun. Severe allergy to the sun can cause skin rashes, blisters or other symptoms. There are several types of sun allergies such as polymorphous light eruption (PMLE), photoallergic contact dermatitis and solar urticaria.
Symptoms
Allergy symptoms depend on the particular type of sun allergy.
Polymorphous light eruption (PMLE)
Symptoms usually appear within a few minutes to several hours after exposure to the sun. Reactions usually begin with itching of the skin and small pustules (pimples), which are whitish or yellowish on red background. Inflammation of the blood vessels can cause the skin to become red and swollen. It can affect the neckline skin, arms and face. Symptoms usually disappear within a few days after making the affected areas protected from the sun. For most people, polymorphous light eruption occurs in spring and early summer. It is the most common type of allergy to the sun.
Contact photoallergic dermatitis
It usually occurs in children and young adults. Symptoms may include itching and red skin bumps that can be expanded on the skin that is not exposed to the sun. Fluid filled bumps can burst and open. It often causes chapped lips, and can affect the cheeks, neck, ears, arms and hands. In some people, it leaves scars. Symptoms usually begin in the summer months and improve by the end of autumn .
Solar urticaria
Symptoms begin within a few minutes of sun exposure and may include rash, itching and pimples. Solar urticaria may affect the exposed areas and areas covered by clothing. It occurs most often in older adults. Symptoms usually improve within an hour after covering the exposed parts of the skin.
When should you go to the doctor?
Visit a doctor if you have unusual, persistent reactions on the skin after exposure to sunlight. For severe or persistent symptoms, you need a visit to a dermatologist.
Causes
Allergic reactions occur when the sun ultraviolet radiation triggers changes in the cells of the skin. These changes cause the immune system mistakenly identify proteins in skin cells as harmful invaders. The immune system then produces antibodies that attack the cells, and this leads to symptoms.
For most people with a sun allergy, exposing bare skin to strong sunlight during the spring or summer causes an allergic skin reaction. However, some people may have a reaction during the winter months.
Certain drugs, chemicals and medical conditions can make the skin more sensitive to the sun. For example, an ingredient in shampoo or lupus can increase sensitivity. In most cases it is not a true allergic reaction. However, it can cause symptoms similar to those caused by sun allergy, and if you already have sun allergy to the sun, it can exacerbate the symptoms.
It is not clear why some people have sun allergy and others do not.
Tests and diagnosis
Your doctor will want to know whether the symptoms are related to sun allergies. Many conditions can cause similar symptoms. In some cases, skin allergies can be diagnosed by answering questions and examining the affected areas when symptoms are present. However, if the diagnosis is not clear, you may have to go for tests to determine what is happening. If this is the case, you will probably have to visit a dermatologist.
Tests for diagnosing reactions on the skin caused by sun exposure may include:
Testing of sensitivity to UV light
It is used to see how your skin responds to different wavelengths of ultraviolet radiation from a special lamp. Determining which specific types of UV light causes a reaction can help you determine you have sun allergy.
Photopatch testing
This type of test is used if the doctor suspects that something you came in contact with makes the skin react to the sun. The doctor will apply two identical substances that may be causing skin reaction. After 24 hours, the doctor will expose one area to UV rays, but not the other. If the reaction occurs only in the area of exposure, your reaction is probably related to that material. This test is generally available only in specialized clinics.
Blood tests and skin sample
These tests are usually not needed. However, the doctor may order one of these tests if suspected symptoms may be caused by conditions such as lupus instead of sun allergy. With these tests, a sample of blood or skin biopsy is used for testing in the laboratory.
Treatments and drugs
Treatment depends on the specific type of sun allergy. It may include:
Corticosteroid creams
These creams are available without a prescription and with a prescription.
Oral antihistamines
These drugs block the histamine which is released during allergic reactions. A doctor may recommend that you use antihistamine without a prescription or with a prescription.
Oral corticosteroids
For severe allergic skin reactions, you can benefit from these powerful anti-inflammatory drugs. In some cases, oral corticosteroids are taken in the period before sun exposure. Oral corticosteroids can cause serious side effects when used long-term, and so they are used for the prevention and mitigation of severe symptoms of allergy to the sun only on short-term basis.
Other drugs
In some cases, drugs commonly used for treatment of other conditions are also used for treatment of an allergy to the sun.
Ultraviolet light therapy
This treatment is also called phototherapy. A special lamp of ultraviolet light is used on areas of the body that are frequently exposed to the sun. This is usually done several times a week over a period of several weeks each spring. During the treatment, the doctor will gradually increase the dose of UV radiation. Your skin gradually becomes accustomed to UV rays and reduces the symptoms caused by sun exposure. This treatment is usually available only in specialized clinics.