Can You Be Allergic To the Sun?

You know that the sun increases the risk of skin cancer for most people. You probably don’t know that for some people, the sun is the source of a terrible itchy rash — they’re allergic to the sun.

The radiation from the sun triggers some response in everyone’s skin. In some, the radiation triggers an immune reaction, leading to red, itchy, burning bumps. There are several diseases that are caused by sun which lead to rashes. Here are a few:

Polymorphous Light Eruption (PMLE): This is the  most common. It is usually characterized by tiny, itchy red bumps that develop on the arms, neck and face hours after sun exposure. It is often seen in the spring and occurs more frequently in young people.

Actinic Prurigo: This is seen as itchy red bumps that occur mostly in children who are sensitive to the sun. Like PMLE, it occurs mostly on the face (including lips), arms, and hands. It can be more severe than PMLE and can lead to scarring in rare instances.

Chronic Actinic Dermatitis: This usually affects adults. It starts in areas exposed to the sun, but can spread to other areas. It is often terribly itchy and can be triggered by sunlight even though car windows.

Solar hives (urticaria): These are itchy pink whelts that develop within minutes of sun exposure. The rash develops quickly and fades quickly but can be intensely itchy. Antihistamines such as Zyrtec (ceterizine) or Benedryl (diphenhydramine) can help.

There are other sun-induced diseases, including ones triggered by medications. I’ll write about them in a future post. In all of these conditions, the most important thing to remember is to avoid sun exposure as much as possible. If you develop an itchy or burning rash after sun exposure, then see your physician for an exam and for advice.

Photo: Sandman (flickr)

Can Exercise Give You Hives?


Hives are itchy pink blotches that develop on your skin. They come up quickly, are extremely itchy, then disappear without a trace in minutes to hours. Many things trigger hives including foods, medicines, and sometimes exercise.

Exercise-induced hives (or urticaria) develop when your skin warms during exercise. Once your skin reaches a certain temperature, itchy welts suddenly bloom. The hives favor your stomach, back, or chest but can occur anywhere. One thing is for certain: They always intensify into a maddening itch.

Eating cheese, seafood, celery, or wheat within a few hours of starting exercise can trigger an outbreak. People who have exercise-induced hives also sometimes react when they take medications such as aspirin, ibuprofen, or naproxen before exercising.

In some people, exercise-induced hives occur when they exercise in cold weather. This often happens when they jog in cold weather, ski, or swim in the ocean (especially here in California where the water is always chilly).

If you’re exercising and you develop an itchy red rash, then stop exercising. If the hives don’t go away within 15 minutes, then stop your workout. Avoid eating cheese, celery, seafood, or wheat  for 4 hours before your workout. Similarly, avoid aspirin or ibuprophen for 4 to 6 hours before exercising. Taking antihistamines such as Benedryl or Zyrtec an hour before exercising may help block an outbreak. Antihistamines also hasten the resolution if taken immediately when the rash occurs.

In rare cases, exercise-induced hives cause swelling of the throat, difficultly breathing, and even death. If you develop swelling of your mouth or throat, or difficulty breathing or swallowing, then seek immediate medical help. Patients with high-risk allergic reactions should carry an epi-pen at all times and should never exercise alone.

Photo: Ernst Moeksis