2. Wei-Qi-Ying-Xue Differentiation

2. Wei-Qi-Ying-Xue Differentiation

This approach divides exogenous febrile diseases into four stages according to their path of transmission: Wei phase, Qi phase, Ying phase, and Xue phase.

(1) Wei Phase Syndrome

Headache, fever, chills (more heat than cold), thirst, dry throat, cough, and a floating, rapid pulse—these are the main symptoms of Wei phase syndrome, treated with Sangju Yin (from the "Differentiation of Warm Diseases") and Yinqiao San (also from the "Differentiation of Warm Diseases").

(2) Qi Phase Syndrome

High fever, intense thirst, profuse sweating, abdominal fullness and pain, severe constipation, red tongue with dry, yellow coating, and a large, forceful pulse—these are the main symptoms of Qi phase syndrome, treated with Baihu Tang (from the "Treatise on Cold Damage") and Chengqi Tang (also from the "Treatise on Cold Damage").

(3) Ying Phase Syndrome

Hot flashes, intense thirst, restlessness, delirium, a red tongue with little coating, and a thin, rapid pulse—these are the main symptoms of Ying phase syndrome, treated with Qingying Tang (from the "Differentiation of Warm Diseases") with added ingredients.

(4) Xue Phase Syndrome

Hot flashes, intense thirst, confusion, delirium, convulsions, rashes, various bleeding symptoms, a dark-red tongue with no coating, and a thin, rapid pulse—these are the main symptoms of Xue phase syndrome, treated with Huaban Tang and Angong Niuhuang Wan (both from the "Differentiation of Warm Diseases").

This differentiation was proposed by the warm disease scholar Ye Tianshi, who built upon the theory of Ying, Wei, Qi, and Xue in the "Inner Canon" while also drawing inspiration from Zhang Zhongjing's Six Meridians differentiation, combining his extensive clinical experience. The Wei phase syndrome is essentially equivalent to the Taiyang syndrome in the Six Meridians differentiation, but with a greater emphasis on pathogenic heat invading the surface; the Qi phase syndrome is essentially equivalent to the Yangming syndrome in the Six Meridians differentiation, but through elaboration on the pathogenic heat lingering in the Sanjiao, it adds heat-related symptoms affecting the lungs and liver/kidneys, making it a more comprehensive representation of clinical manifestations than the Yangming syndrome in the Six Meridians; the Ying phase syndrome is a further deepening and development of the Qi phase syndrome, with the main characteristic being that excessive heat damages yin; the Xue phase syndrome is a further development of the Ying phase syndrome, with the main characteristic being that excessive heat damages yin while simultaneously causing heat to affect the pericardium, leading to uncontrolled bleeding, and even triggering wind-like symptoms due to extreme heat.