Dermographia is a dermatological condition that causes red lines, sometimes known as wheals or welts, to develop when a sufferer's skin is scratched or rubbed. It is also known as dermatographia, dermatographic urticaria, or "skin writing." Wheals are a type of hive and are not dangerous, but they can be itchy and uncomfortable. The marks usually last for just a few minutes, though in severe cases, they could linger for hours or days. There is no cure for the condition, though it is often possible to control outbreaks through a combination of lifestyle changes and taking oral antihistamines.
In patients with dermographia, even superficial scratching causes small blood vessels in the skin to dilate, or widen, and a wheal to form. Often, the swelling follows the line of the scratch, appearing as a raised red line on the skin. These hives or wheals may be itchy or, in rare cases, have a burning sensation.
The lines and wheals form with five minutes of the skin being scratched or stroked, in most cases, and disappear within 30 minutes. A form called delayed dermatographism does not exhibit symptoms for several hours after the initial trigger, and the hives can last for a day or longer. This condition may come and go, but people often experience
Causes and Frequency
Mast cells are a type of immune cell found in the skin, mucous membranes, and other tissues. When an allergen enters the body, these cells are stimulated, releasing chemicals called histamines that cause a runny nose, swollen eyes, rashes or hives, and other symptoms of an allergic reaction. In a person with dermographia, the mast cells become overly sensitive to minor trauma, and cause hives to appear on the skin when it is rubbed or scratched.
Experts are not sure what causes the mast cells to become overreactive. Some believe it is associated with allergies, since mast cells play a big role in allergic reactions, but others dispute this. Many sufferers have no other allergy symptoms and no specific allergen seems to trigger the condition.
Some people choose to undergo allergy testing anyway, in case the hives are triggered by — or made worse by — an identifiable cause. For example, some drugs, including penicillin, can cause a rash or hives. The most appropriate type of allergy test is a blood test, since traditional "scratch tests" or patch tests require rubbing the suspected allergens on a patient's skin. This can cause a reaction in someone with dermographia unrelated to the actual allergen.
Around 4% - 5% of people have dermographia, and it is considered one of the most common forms of urticarias, or disorders that produce hives. It tends to be more common in people in their 20s and 30s, and is equally common in men and women.
While dermographia can’t be prevented outright, there are things that a person can do to minimize how frequent and how severe the outbreaks are. Those with the condition can make a point of identifying possible triggers and avoiding them. Possible triggers include wearing irritating fabrics, like wool, or using harsh soaps or personal care products. Some people find that eliminating fabric softener can also help prevent clothing-based reactions. Although this condition is not known to be caused by a specific allergy, it is possible that an allergic reaction could make the problem worse, so anything known to cause a reaction should be avoided.
Keeping the skin moisturized may also help. People with the condition should drink plenty of water and use a moisturizing lotion to reduce the chances of developing dry skin, which may encourage more scratching. Both heat and cold may trigger an outbreak, so things like bathing in very hot water may cause welts to form, so sufferers should adjust their hygiene routine to see if it offers relief.
Hives can develop as a result of stress, so someone who already has dermographia may find that the condition gets worse during particularly stressful times. Finding ways to relax and reduce anxiety may make the wheals less common.
Treatment and Prognosis
An outbreak of skin wheals caused by dermographia will usually go away on its own relatively quickly, so there is often no need to treat the condition. People who are extremely prone to outbreaks or who find the condition very uncomfortable may be treated over-the-counter or prescription oral antihistamines. Sometimes, a combination of drugs is needed to provide relief.
While antihistamines may reduce the symptoms, there is no known cure for this condition. In many cases, an outbreak may last for several months or years and then disappear. The wheals may eventually return for some sufferers, however.