Dermatographia, also called skin writing, is a condition that causes an allergic reaction when skin is scratched. This reaction looks like hives or welts. It may even happen when the skin is rubbed when pressure is applied.
Experts estimate that 2% to 5% of people have dermatographism. It’s quite common and isn’t dangerous.
Symptoms of Dermatographia
If you have this condition, you get raised red welts where your skin was recently scratched or irritated. These welts or hives develop within 5 to 7 minutes of scratching and usually fade away within 15 minutes to half an hour. In rare cases, the symptoms develop more slowly and may take hours or days to disappear.
This condition is known as skin writing because you can make writing or drawings appear on your skin by stroking it with an object, like your fingernail or a closed ball-point pen. At first, your skin will turn white. Then the redness and swelling will begin, taking the form of the strokes you made.
The symptoms of skin writing can be different for each person, but there are some common signs:
- Swelling
- Raised red lines that form in the same pattern as your fingernails
- Itching
- Welts that look like hives or raised patches
- Inflammation
Causes of Dermatographia
Experts aren’t sure of the exact cause of dermatographism. It could be an allergic reaction, but no specific allergen has been found.
Doctors believe that the welts form because of a release of histamine, a chemical that your body makes when it suspects an invading allergen. The histamine causes welts and hives, which are an overreaction because there is no allergen present.
Skin writing may also flare up because of things like:
- Exercising
- Vibration
- Exposure to heat and cold
- Stress
Some things may make people more likely to have to dermatographism. Doctors think that people with other skin conditions might be more at risk. These include:
- Dry skin
- Eczema
- Dermatitis
Symptoms of dermatographia can be triggered by simple things or actions. Your clothing or bedsheets rubbing against your skin can cause a reaction. Pressure from leaning or resting on a hard surface can also trigger the hives. Research suggests that there might also be a link between skin writing outbreaks and taking penicillin.
In rare cases, dermatographia can be triggered by infections such as:
- Scabies
- Fungal infections
- Bacterial infections
People of any age can have dermatographia, but it is most common in teens and young adults. You may have it for a short time, like a few months. Or it could be chronic and last years.
Diagnosis and Treatment of Dermatographia
Your doctor can diagnose dermatographia with a simple test. They use a tongue depressor or other tool to gently stroke your skin, drawing lines. They watch for welts to show up within a couple of minutes.
There’s no cure for dermatographia. And because the symptoms usually go away very quickly, you probably don’t need treatment. But some people may find their hives are very itchy or bothersome.
Medications. Your doctor may prescribe an antihistamine to help ease the symptoms of dermatographia. Antihistamines help manage symptoms of allergies. Many are also available over the counter.
A medication called cromolyn has the same effect as antihistamines. It helps stabilize the cell membrane that releases histamine and eases symptoms. Cromolyn requires a doctor’s prescription.
Preventive care. There are a few things you can do to prevent symptoms. First, avoid irritating your skin. This includes wearing soft, loose clothing and avoiding harsh or scented soaps. Hot water during showers can also make dermatographia worse, because heat may be a trigger.
Second, keep your skin moisturized. Apply lotion or cream after showering to hydrate your skin, as dry skin tends to get itchy.
Avoid scratching your skin. It only makes dermatographia worse. The more you scratch, the worse your symptoms will be.
