Dermographia, also known as dermatographia, is a skin condition that causes itchy, red lines to appear when a person affected with the disorder scratches his or her skin. The lines that appear from dermographia are not serious, but they can be itchy and uncomfortable. In addition, these lines can last for several minutes after scratching is complete.

In a person with dermographia, specific skin cells called mast cells have a tendency to be overly sensitive when they experience minor trauma, such as that experienced when a person scratches his or her skin. When a person with dermographia scratches his or her skin, it causes the mast cells to release special chemicals called histamines. When histamines are released in a person with dermographia, the small blood vessels dilate. As the blood vessels dilate, or widen, it causes the characteristic redness and itching associated with dermographia.

Experts are unsure of the cause of dermographia, though most believe it is associated with allergies. Despite this belief, several patients afflicted with dermographia have no other symptoms of allergy. A person with dermographia can avoid symptoms by refraining from scratching his or skin or irritating it in any way. It is also best to avoid wearing wool clothing, which can scratch against the skin and cause the lines to appear. Harsh soaps also appear to irritate the condition.

In some cases, antihistamines are prescribed to help treat dermographia. Other times, the dermographia goes away on its own. For some people, the condition never really goes away.

Determining whether or not dermographia is associated with allergies can be difficult if the allergies are not already identified. This is because a common method for testing for allergies involves rubbing various allergens against the skin. Since the skin of a person with dermographia is irritated by rubbing, every allergen will appear to cause a reaction.

For individuals with dermographia, it is necessary to perform blood testing rather than skin tests to determine possible allergens. If the test indicates a specific allergy, the person with dermographia may receive allergy injections to help battle it. This does not, however, guarantee that the deromgraphia will subside, because the allergy is not necessarily the cause of the condition.