How Does a Sun Rash Form?

What Causes Sun Rash

Polymorphic light eruption, more commonly known as "sun rash," usually is caused by sensitivity to light, most often triggered by exposure to sunlight. Although the rash can take different forms, raised pink or red spots typically appear on the V of the neck, arms, and back of the hands. The rash may be seen on the chest and lower legs as well. In some cases, the rash resembles dermatitis, where the affected area may be covered in small blisters, followed by large, dry, red patches. Women between the ages of 20 and 40 who have fair skin are those most affected, although anyone can develop sun rash if out in the sunlight too long.

Other Causes

The ingredients contained in some sunscreens, cosmetics, suntan lotions, cortisone creams or antibiotic ointments applied to the skin can trigger a reaction when exposure to sunlight occurs. Taking common medications, including antibiotics, certain oral contraceptives and diuretics used to treat high blood pressure can cause photosensitivity in some people. Recent research also has linked nonprescription pain relievers such as ibuprofen and naproxen sodium to photoallergic reactions. The condition can be inherited as well.

Symptoms

An immune reaction of the skin to the sun's ultraviolet rays, sun rash typically causes itching or a burning sensation that can last for several days. The rash usually clears up within a few days if further prolonged exposure to sunlight is avoided. An allergic reaction to sunlight, individuals often experience the condition in the spring when they first go outdoors and spend several hours in the sunshine. Sun rash can get worse if you go out in the sun again before it heals. In most cases, though, the skin becomes less sensitive to sunlight, as the warm weather season advances and more time is spent outdoors.

When to Seek Medical Advice

You may need to see your primary care physician or dermatologist if you suffer a persistent rash on the areas of your face exposed to the sun or if the rash spreads to those areas of your body covered by clothing. Call your doctor if you have an itchy rash that does not respond to over-the-counter treatments. Any rash accompanied by a high fever or extreme pain should be reported to your doctor. Summon emergency medical assistance immediately if you suddenly develop hives and vomiting, along with swelling of your lips or eyes following exposure to the sun. These symptoms together with difficulty breathing or swallowing, confusion or unconsciousness could be signs of a life-threatening allergic reaction.