The Six Pernicious Influences: Wind, Cold, Heat, Dampness, Dryness, Summer Heat

What the term means

In traditional Chinese medicine (TCM), the "six pernicious influences" (liu yin, sometimes translated "six excesses" or "six evils") are climate-like forces that are said to cause illness when they are excessive or arrive out of season. A museum exhibit on Chinese medical texts from the National Palace Museum in Taipei states that, according to traditional theory, illness is caused by the Six Pernicious Influences (wind, cold, heat, damp, dryness and fire), disturbances of the Seven Emotional States, exhaustion, over-indulgence and an unhealthy diet. These lead to imbalances of yin and yang, cold and hot, and qi and blood, eventually shown as disorders of the "five viscera and six bowels". [1]

These are traditional frameworks. They are not environmental-health findings, and they are not the same as germs, allergens or pollutants. Lists vary slightly: some sources give "summer heat" as a sixth separate influence, others list "fire".

The six, and how they are described

The names are weather words used as images: wind (moving, changing), cold, summer heat, dampness, dryness, and fire or heat. Exact descriptions differ between texts and schools, and the list is not applied to a person by quiz or checklist. A practitioner decides using the whole consultation; this page does not offer a way to diagnose yourself. See Traditional Pattern Differentiation, Eight Principles Pattern Analysis and Cold, Heat, Dampness, Phlegm for how the terms are used.

Outside and inside

In the classical fever frameworks (the Shanghan lun and the warm-disease schools), an outside influence is described as entering at the body's surface, where the defensive layer is affected at the early stage. [2] See Wei Qi (Defensive Qi). Sources also speak of similar-sounding states arising from within when organ function is out of balance; the wording varies by author.

What has research tested?

Proper evidence not found for the six influences as causes of disease. I searched the sources available this session (NCCIH, PubMed and practitioner publications) and found descriptions of the theory, but no trial or cohort study that tests "wind", "dampness" or similar influences as defined causes. That does not say anything about weather and health in general; it means the traditional categories themselves were not found tested as measurable causes.

What exists instead is research on specific treatments used by TCM practitioners. NCCIH summarizes that some approaches such as acupuncture and tai chi may help certain pain conditions and quality of life, while studies of Chinese herbal products have had mixed results and were often poor quality. [3] Those findings concern the treatments, not the six-influence theory. Label: traditional use only.