Dermatographia is a condition also known as skin writing. When people who have dermatographia lightly scratch their skin, the scratches redden into a raised wheal similar to hives. These marks usually disappear within 30 minutes. The cause of dermatographia is unknown, but it can be triggered in some people by infections, emotional upset or medications such as penicillin.
Dermographism can be treated by substances which prevent histamine from causing the reaction (i.e. an antihistamine). These may need to be given as a combination of H1 antagonists, or possibly with an H2-receptor antagonist such as cimetidine. Not taking hot baths or showers may help if it is generalized (all over) and possibly for localized cases (in a specific area). If it affects mainly the head, it may be psoriasis. In rare cases, allergy tests may uncover substances the patient is allergic to. Using biodegradable or hypo-allergenic soaps and laundry supplies may help. Using menthol mixed with aqueous cream is often an excellent temporary solution to help reduce irritation and itching in a localised area. While cromoglycate, which prevents histamine from being released from mast cells, is used topically in rhinitis and asthma, it is not effective orally for treating chronic urticaria. Bug spray may also cause the skin reaction. Frequent anecdotal evidence suggests taking in small amounts of alcohol may help with the itching, or temporarily cause the inflammation/welts to subside. Acupuncture and Chinese herbs have long been used to treat urticaria in Asia.