Dermatographism can be caused by stress, tight or abrasive clothing, watches, glasses, energetic kissing, heat, cold, or anything that causes stress
to the skin
It can be treated by antihistamines or cromoglicate and
sometimes steroids, as they prevent the histamine from causing the reaction. As the underlying cause of dermographism is not known, it can last for many years without relief.
I hope it helps. Take care and regards.