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10 most bizarre allergies

Jan. 17, 2011, 11:05 a.m.
dermatographism

Photo: Wikimedia Commons

10 of 12

Touch

People with dermatographia are sensitive to pressure and touch, and depending on the severity of the case, even a slight touch can trigger an allergic episode that creates a raised, itchy red rash. It is unknown why this allergy occurs, but it's estimated that 2 to 5 percent of the population has it. Because words and designs can easily be scratched on the skin, the condition is often referred to as “skin writing disease.”