Summer-heat is a yang pathogenic factor characterized by sweltering heat.

If pathogenic summer-heat attacks the body, the clinical manifestations are yang-heat, syndromes, such as high fever, burning heat sensation of the skin, irritability, forceful and rapid pulse, etc.

Summer-heat consumes qi and yin (body fluid), and is characterized by upward direction and dispersion.

Invasion of pathogenic summer-heat to the head region causes dizziness, vertigo, and excessive sweating due to the abnormal opening of the pores. Excessive sweating exhausts the qi and body fluid and manifests as thirst with desire to drink, dryness of the lips and tongue, constipation, yellowish and concentrated urine, etc.

Pathogenic summer-heat often combines with damp to cause diseases when the temperature and air humidity are very high.

If summer humid-heat attacks the body, the manifestations are fever, heavy sensation of the head or even the whole body, stuffiness and fullness of the chest and epigastric regions, nausea, vomiting, abdominal distension, diarrhea, etc.

Pathogenic factors in summer are summer-heat, sun-stroke and summer humid-heat.

Main clinical manifestations of summer-heat: fever, excessive sweating, irritability, thirst with preference for cold drinks, shortness of breath, lassitude, general weakness, scanty and yellowish urine, rapid and xu (weak) pulse.

Main clinical manifestations of sun stroke: dizziness and vomiting for mild cases; sudden collapse, unconsciousness, profuse and cold sweating, cold extremities, forceful and xu pulse for severe cases.

This group of symptoms are caused by strong sun heat that internally affects the body qi activity leading to sudden prostration of qi and body fluid.

Main clinical manifestations of summer humid-heat: fever, irritability, stuffy chest, nausea, vomiting, anorexia, lassitude, loose stools, yellowish urine, soft pulse, yellow and sticky tongue coating, etc.

The symptoms resulting from summer humid-heat invasion include the common symptoms of summer-heat, such as fever, irritability, yellowish urine, etc., and the symptoms caused by the obstruction of dampened qi circulation, such as stuffy chest, nausea, vomiting and anorexia. Furthermore, there are also the symptoms of internal dampness, such as loose stools, soft pulse, sticky tongue coating, etc.