Alternate cold and fever means that aversion to cold and fever occurs alternately due to struggle between healthy qi and pathogenic factors, signifying development and abatement of cold and fever. Irregular alternate cold and fever is seen in shaoyang disease pertaining to semi-internal and semi-external syndrome due to struggle between healthy qi and pathogenic factors. The predomination of pathogenic factors leads to aversion to cold, while the predomination of the healthy qi leads to fever.

If pathogenic factors and healthy qi predominate alternately, it leads to alternate cold and fever. Regular cold and fever, once a day or once two and three days, accompanied by severe headache, thirst and profuse sweating, pertains to malaria.? When pathogenic factors invade the body, they stay in the semi-internal and semi-external region. When they get inside, they struggle with yin; and when they get out, they struggle with yang. That is why chills and high fever appear alternately and continually.