80% of urticaria in children is caused by common cold

Urticaria is an itchy, swollen rash that disappears within 24 hours but appears as if it has moved to another location.
 There is also “stimulus-induced urticaria” with a definite cause, but most cases in children are “idiopathic urticaria” with no identifiable cause.
 The cause of “acute idiopathic urticaria,” which resolves within one to four weeks, can be stress or fatigue, but most cases are caused by a cold virus that entered the body before or after the onset of urticaria. Therefore, once the cold is cured spontaneously, the urticaria will also heal on its own.