Heat

1. The opposite of cold. Heat is the manifestation of the sun and fire. Hot weather (and artificially heated environments) cause sweating, and without an adequate increase in fluid intake, thirst. There may be vexation and other discomforts naturally attributed to heat by the individual. In the healthy individual, these natural responses abate on exposure to cooler temperatures.

2. The external evils fire and summerheat manifesting in the body in pathological signs such as high fever, fear of heat, desire for coolness, thirst, red face, red eyes, reddish urine, red tongue with yellow fire, and rapid pulse. Fire and summerheat are two of the six excesses. They result from exposure to heat in the environment or to spells of weather that are abnormally hot for the season.

3. Any condition manifesting in signs similar to those of fire and summerheat that are the result of a) yīn vacuity or b) the transformation of either external evils passing into the interior or of the transformation of yáng qì as a result of affect damage (physiologically disruptive effects of emotional and mental states). See fire.

4. One of eight parameters under which any of the above pathological conditions are classified. The terms that describe the action of heat in the body that produces heat patterns include:

• Blaze (燔 fán), to burn vigorously (e.g., qì and provisioning both ablaze);
• Deflagrate (焚 fén), to burn intensely (e.g., heart fire deflagrating internally);
• Effulgent (旺 wàng), burning brightly (e.g., yīn vacuity with effulgent fire);
• Steam (蒸 steam), to rise gently upward or out to the surface (e.g., steaming bones);
• Fume (燻（薰） xūn), to produce heat without flaming.
• Flame upward (上炎 shàng yán), (of fire) to rise like a flame to produce upper body signs. (e.g., liver fire flaming upward);
• Glow (烁 shuò), to burn without pronounced flaming.
• Scorch (灼 zhuó), to damage slightly by burning (e.g., evil heat scorching the network vessels);
• Condense (炼 liàn), reduce fluids (producing phlegm).

5. Heat effusion or subjective sensations of heat that may or may not be classified as heat among the eight principles.

6. One of the four natures (heat, cold, warmth, coolness) of medicinals, used in the treatment of cold patterns.

NB: The term heat is distinguished from fire, summerheat, and warmth as follows. Fire in the context of the six excesses means heat in the broad sensebut may also denote intense heat as opposed to the milder form, warmth. Heat occurring between the summer solstice and the autumn equinox is called summerheat, in contrast to fire and heat, which usually denote heat occurring at other times of the year. Heat and fire may also denote states arising within the body as a result of transformation of other evils or of yáng qì. In this context, fire denotes more intense forms of heat, as in extreme heat transforming into fire and damp depression transforming into fire, and specifically denotes heat that manifests in upper body signs, e.g., liver fire flaming upward and heart fire.