Sunday, May 1, 2011

Photodermatitis - Sun Allergy And Its Causes


Many people suffer from redness and itchy eruptions on the uncovered parts of the skin such as face, neck and hands which become worse whenever they go out in the sun. Such symptoms are suggestive of photodermatitis or sun allergy. 


In this post I will discuss photodermatitis in detail, including the common symptoms and signs, as well as its causes. First, let's see what exactly is photodermatitis.


What is Photodermatitis?

An acute or chronic inflammatory reaction of the skin, caused by hypersensitivity to the sunlight or ultraviolet rays, is known as photodermatitis. It is a form of contact allergic reaction commonly manifested as-

1. Photosensitivity

When a person shows a tendency to develop sunburn more easily compared to others.

2. Photoallergy

It is an immunologic reaction manifested clinically as papular or vesicular eruptions.

What causes Photodermatitis?

Photodermatitis occurs as a result of an immunologic reaction produced by interaction of light rays and certain chemicals.

1. Some of the substances which may act as photocontact allergens are-

  • Sunscreen agents
  • Optical bleaches
  • Topical antihistamines
  • Perfumes
  • Anti-septics

2. Skin may become photosensitized by certain drugs.

3. Hypersensitivity to radiation can be seen in some constitutional disorders.

4. May be associated with a hereditary disorder.

5. Some cases may be idiopathic where the photoallergy is not associated with any photosensitizing agent.

Symptoms And Signs Of Photodermatitis

Patient usually manifests the following symptoms and signs-

#1. Erythema (redness), edema (swelling), papules or vesicles associated with pain or itching.

#2. Peeling of skin.

#3. Skin discolouration.

#4. The lesions or rashes are localized to the sun exposed areas like face, neck, hands, and the exposed part of the chest.

#5. Inner upper eyelids and the area under the chin are usually not affected.

#6. However, these lesions may become generalized with time and the covered areas of the body also become affected.




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