Mugwort is a very common herbal medicine in the clinic, with the effect of warming the menstruation and stopping bleeding, dispersing cold and relieving pain, patients with severe itching sensation on the body consider the occurrence of skin allergies, skin allergies are not recommended to apply mugwort for external washing to relieve itching. Skin allergy occurs when the skin is in a highly sensitive stage, self-scratching will lead to conditions such as hives, which can occur repeatedly and aggravate, then self-application of mugwort for bathing, may cause the patient to occur hives and other allergies significantly aggravated, then mugwort to the patient is equivalent to a new allergen and contact to the skin.