What is sunlight urticaria?

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Sunlight urticaria is a rare allergic reaction to sun exposure. This sun allergy causes an itchy rash or hives to appear on any exposed skin. The more the skin is exposed to the sun, the more severe the reaction. However, there is no cure for sunlight urticaria. Since it is a chronic condition, the person needs to avoid the sun almost completely.

1. What are the symptoms of sunlight urticaria?

The symptoms of sunlight urticaria are the sudden onset of a rash or hives (solar dermatitis). It may only take a little time in the sun to trigger a reaction. Allergic reactions to the sun are usually limited to areas of skin exposed to the sun.
Accordingly, symptoms of sunlight urticaria include:
Blisters or rash Many small bumps that may merge into larger patches Pain or itching Redness of the skin Flaking of the skin Scaling or bleeding In addition to the symptoms Some people with sun allergy also report additional symptoms, such as headaches, fatigue, nausea, and changes in heart and breathing rates. Symptoms may worsen if large areas of skin are exposed to sunlight. In rare cases, solar urticaria can lead to anaphylaxis, a potentially life-threatening condition.
However, the symptoms of sun allergy urticaria usually begin to subside after exposure is stopped. The rash usually clears up quickly within 24 hours, as long as you don't continue to be exposed to the sun.

2. What is the cause of sun allergy?

Sunlight urticaria is a rare disease, the cause of which is currently unknown. Experts believe it is an immune response. Your immune system misidentifies sun-affected cells as foreign cells. That causes a Histamine reaction, which leads to redness, inflammation, itching, and other symptoms.
People of any race can develop sunlight urticaria, although it is more common in people with light skin. It usually develops in adults over the age of 30 and may be more common in women than men. People who are already allergic or have sensitive skin may also be more sensitive to sunlight.

3. How to treat solar urticaria?

Sunlight urticaria develops skin lesions that usually last a lifetime. There is no complete cure for the disease other than preventing sun exposure and controlling symptoms as the mainstay of treatment.
Accordingly, the patient almost absolutely avoids exposure to the sun. Keeping skin out of direct sunlight can reduce the frequency of sun allergies. When you need to go out, you need to wear loose clothing that covers your chest, arms, and legs. Wide-brimmed hats and sunglasses can protect your face. You may feel most comfortable indoors or in the shade during the hottest times of the day.

3.1. Sunscreen

Wearing sunscreen can protect your skin from some sun exposure. Researchers have found that UVB rays are more likely to cause a reaction, so you should look for sunscreens that block UVB rays.
Furthermore, physical sunscreens that block or reflect sunlight may be more helpful than chemical sunscreens, which are formulated to block UVA rays. Ingredients like titanium and zinc often work to deflect UVB rays and prevent solar urticaria reactions. You should reapply sunscreen often when going outdoors.

3.2. Antihistamines

Since sunlight urticaria is an allergic disease, allergy medications can be helpful in controlling flare-ups. Antihistamines control the release of histamine that causes rashes and sun-exposed dermatitis.
The doctor will recommend the most effective medicine. You may need a higher dose than usual, so be sure to ask your doctor about the proper dosage.

3.3. Lights

Your doctor may recommend using phototherapy to create controlled light exposure for short periods of time to increase sun exposure. This therapy uses the same principle as allergy shots, in that you receive small doses of allergens to desensitize them over time.
During lighting, you will need to double-check to determine how different wavelengths of light affect you. Your doctor will then establish an incremental course of treatment to improve your tolerance to sunlight.

3.4. Asthma medication

Certain asthma control medications are helpful for controlling sunlight allergies.

3.5. Immunotherapy

If the above basic treatments don't give you the desired effect, you may need to take an immunosuppressant to suppress the histamine reactions. Research shows that infusion of immunoglobulins or plasma exchange is also useful for the management of solar urticaria.
In rare cases, sunlight urticaria may spontaneously disappear completely. Researchers estimate that 15% of people with solar urticaria have spontaneous recovery 5 years after diagnosis. Furthermore, spontaneous recovery increased to 25% after 10 years.

In summary, sunlight urticaria is a condition of sun allergy. While treatment has so far been complex, the condition can have a significant negative effect on a person's quality of life. Therefore, because avoiding daylight makes normal activities difficult, it is important to talk to a doctor whenever you feel that your physical or mental health is seriously being affected in order to receive help. suitable support.

References: dermnetnz.org, ncbi.nlm.nih.gov, healthline.com, webmd.com

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This article is written for readers from Sài Gòn, Hà Nội, Hồ Chí Minh, Phú Quốc, Nha Trang, Hạ Long, Hải Phòng, Đà Nẵng.