Solar urticaria, also known as “sun rash”, is a rare inflammatory skin condition in which exposure to sunlight causes raised red or white welts to appear on the skin. At times, the symptoms can be confused with a sunburn, but are generally similar in appearance to hives. The welts can often appear within a few minutes of sun exposure, and can go away quickly (in most cases less than a day) once sun exposure has stopped. The rash typically disappears without leaving any permanent marks. Skin that is frequently exposed to the skin, such as the face, is less likely to develop rashes. Although there is no definitive cure for solar urticaria, there are treatment options, which can reduce the severity of the symptoms.
Common features of solar urticaria include:
Welts: Raised, red welts appear on the skin
Rash: An itchy rash that may spread to other areas of the body
Pain: Stinging or burning sensation in the affected area
Solar urticaria is caused by a hypersensitivity to UV radiation. When sunlight reaches the skin, it results in the release of histamine and histamine-like substances from cells called “mast cells” in the dermis. These cells have multiple receptors, that when activated, permit the discharge of the products contained in tiny packages in the skin. Substances that are released into the bloodstream, such as histamine, allow blood vessels in the dermis to dilate, creating a red appearance and also causing water to leak into the skin, which produces swelling.
Because of the sensitive and inflammatory nature of this condition, great care needs to be taken when choosing skincare products.Avoid soaps, especially bar soaps, as they will cause dry skin and may damage the skin barrier. Instead, opt for mild soap-free cleansers, preferably in liquid form. These cleansers will gently remove dirt, excess oil, bacteria and cosmetics without damaging the skin barrier. Hot water can actually dry out the skin further. Moisturizers help to restore and maintain the skin’s natural moisture levels. Look for moisturizers specially designed for sensitive skin that are free of fragrance, dye or other allergens that may irritate the skin. Frequent application of moisturizing creams can help soothe dry and itchy spots.If you experience severe itching, do not scratch the affected area, as it can lead to scarring, increased pigmentation (darkening of the skin), thickening of the skin, or infection. Instead, gently pat the skin, or apply a damp compress for relief.
Overall, the best course of action to prevent solar urticaria is sun avoidance and protection.
Limit sun exposure: Avoiding UVA light is the only surefire way to prevent this condition. When outdoors, set a time limit and seek shade when necessary. Also keep in mind that UV radiation is the strongest between the hours of 10 a.m. to 4 p.m.
Use Sunscreen: Sunscreens are an essential part of protection against the sun. Look for sunscreens that are labeled “Broad Spectrum”. They are often the most effective and offer protection against both UVA and UVB rays. Make sure to apply generously and frequently.
Cover and protect: Wrap-around sunglasses, wide-brimmed hats and clothing that covers your arms and legs, can offer extra protection against the sun’s harmful UV rays.
Taking an oral antihistamine can often help reduce the symptoms of solar urticaria by blocking the histamine receptors in the skin, which produces the symptoms of urticaria. Diphenhydramine (Benadryl) is considered one of the most effective medications for treating hives and solar uriticaria, but can cause drowsiness. A doctor may suggest non-sedating antihistamines such as Cetirizine (Zyrtec), Fexofenadine (Allegra) or Loratadine (Claritin).
A doctor may prescribe oral corticosteroids to help relieve swelling redness and itching. Procedures Light therapy (phototherapy) can also be used to treat solar urticaria. Controlled and repeated exposure to low doses of UV light can help desensitize the skin, making it more resistant to allergic reactions.