Dermatographia
If after lightly scratching your skin, your fingernails leave thin, raised red welts on your skin that take 15 to 30 minutes to disappear, you may suspect dermatographia. Although the cause of this condition is unclear, the Mayo Clinic says it could be triggered by stress, infections, allergens, or medications like penicillin. “It’s an extreme skin condition, where your skin is sensitive to touch and releases too much histamine,” says Dr. Rokhsar.