1. Externally contracted febrile diseases. Plain Questions (素问 sù wèn, rè lùn) states, Heat (febrile) diseases are all of the cold damage kind. It also states, When a person is damaged by cold, the disease is febrile (one of heat). This notion of cold damage was elaborated in On Cold Damage (伤寒论 shāng hán lùn), which understands externally contracted febrile disease in terms of the penetration of external evils through six levels named after the yīn-yáng designation of channels (greater yáng (tài yáng), yáng brightness (yáng míng), lesser yáng (shào yáng), greater yīn (tài yīn), lesser yīn (shào yīn), and reverting yīn (jué yīn)). See six-channel pattern identification.
2. A specific form of externally contracted febrile disease, The Classic of Difficult Issues (难经 nàn jīng) states, Cold damage has five [forms]: cold damage, wind stroke, damp warmth, externally contracted febrile disease, and warm disease. This specific form of febrile disease is elaborated on in On Cold Damage (伤寒论 shāng hán lùn), i.e., a greater yáng (tài yáng) pattern of externally contracted febrile disease with absence of sweating, stiff neck, and a tight floating pulse.
3. A disease caused by catching cold in the winter.