Erythema multiforme is an acute inflammatory pathological change of the skin and membrane and often occurs in spring and autumn or winter in the young adults, characterized by localization, easy recurrence and unknown causative factors. Maybe, it is an allergic reaction to medications, tumors and infections. "Cat Eye Boil", "Swallow Boil" and "Cold Boil" explained in Chinese medicine are similar to this disease.

It is believed in Chinese medicine that this disease is caused by internal accumulation of dampness and heat in the spleen and stomach, accumulation in the muscle and skin after invasion of exogenous wind, or by qi stagnation and blood stasis due to exterior blockage of wind and cold and disharmony between Ying-Nutrient Qi and Wei-Defensive Qi.