yin yang sign with needleAccording to traditional Chinese medicine (TCM) theory, disease can be caused by either internal or external factors. 

The internal factors that cause disease include the seven emotions; joy, anger, worry, overthinking, grief, fear and fright. These are considered healthy when expressed appropriately, but when one emotion is held on to over a long time period, this can cause problems.

The external factors are things such as extreme climates, diet and lifestyle. They include what are known as the ???six evils??? or ???six excesses???; cold, heat, summer heat, dampness, dryness and wind. These may sound more like something you would hear in a weather report rather than a doctor's office, but there is a good reason for that.

In ancient times, when TCM was just emerging, doctors understood the body in a very different way. They based their diagnosis on what they could see in nature and observe in the human body. They noticed that certain diseases behaved in a particular way, similar to the weather and the environment around them. This is how the theory of the six evils was born.



Cold can develop due to spending too much time in a cold environment or not wrapping up warm enough in cold weather. It can also be caused by too many cold or raw foods in the diet.

We all know that cold temperatures turn water into ice. In the same way, inside the body, cold causes blood and qi to become thick and sluggish leading to stagnation. Processes such as digestion also become weakened over time.

kid in t-shirt shovels snowThe symptoms of cold include:

  • Chills
  • Cold limbs
  • Pale skin
  • Pale urine
  • Sharp, stabbing pain or cramps
  • Weak digestion
  • Loose stools

Cold can be prevented by wrapping up warm during the winter and eating warming foods. Spices such as ginger and cinnamon are good for warming the body as well as foods like onions, red meat and seafood. Avoid cold and raw foods and drink your beverages warm or at room temperature rather than iced. 



Our bodies need a certain amount of heat in order to carry out their vital functions, but if it becomes excessive, disease can occur. Heat can make you feel anxious and agitated as well as leading to dryness in the body.

Heat can be caused by emotional stress, eating too many spicy or fried foods, or by what is known in TCM as yin deficiency. When heat becomes very extreme, it can lead to another condition known as fire.

The symptoms of heat include:

  • Feelings of heat in the body, especially the hands, feet and chest
  • Excessive thirst
  • Dry mouth or throat
  • Dry stools and constipation
  • Dark, scanty urine

You can calm heat down by eating plenty of cooling foods such as citrus fruit, squashes and tofu. Avoiding stress as much as possible is another good way to keep heat at bay.


Summer Heat

Summer heat is caused by prolonged exposure to high temperatures. It is very similar to what we call sunstroke in the West.

The symptoms of summer heat include:

  • Sweating
  • Shortness of breath
  • Dizziness
  • Nausea

Avoid summer heat by limiting your exposure to the sun. Wear sunscreen and a hat during hot weather, stick to the shade and be sure to stay well hydrated.

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Dampness can be caused by living in damp conditions or too many rich, fatty foods in the diet. These kind of foods are hard to break down and put a strain on your digestive organs. This results in a build up of fat in your system, and in TCM, that means dampness.

People who are overweight often have issues with dampness from a TCM perspective, although not everyone who has dampness will be overweight.

Other symptoms of dampness include:

  • Fatigue
  • Heavy, numb or aching limbs
  • Edema
  • Difficulty thinking clearly
  • Sticky mucus or phlegm

The best way to combat damp is by eating a healthy diet and avoiding too many creamy, fatty or greasy foods. If you get wet, make sure that you dry yourself properly as soon as you can, and avoid going to bed with wet hair.



Dryness is closely related to heat and the two often exist together. Dryness simply means that there is an insufficiency of moisture in the body. It especially affects the Lungs and skin.

Symptoms of dryness include:

  • Dry skin and lips
  • Dry cough
  • Dry stools
  • Constipation

Dryness can be avoided by moisturizing regularly and using a humidifier in your home.



Wind is sometimes called ???the spearhead of disease??? in TCM. It can easily penetrate the body's defences, often bringing heat or cold along for the ride. Wind is thought to attack when you fail to protect yourself properly by wearing enough layers, especially around your upper back and neck.

Because wind is light and insubstantial, it moves around the body causing quickly changing symptoms or symptoms that come and go. It is responsible for causing what we now know are viruses such as colds and flu.

Symptoms of wind include:

  • Sneezing and nasal congestion
  • Headaches
  • Itching
  • Muscle spasms
  • Tics or tremors

The best way to protect yourself against wind is by wrapping up well when you go out in windy weather and trying to keep your immune system healthy with good food and exercise.


Why are the Six Evils Important?

The six evils are an important tool in diagnosis and treatment with TCM. When your practitioner feels your pulse and looks at your tongue, this is partly to see whether any of the six evils are present.

By putting this information together with your individual symptoms, they are able to form a treatment plan and give you lifestyle advice which addresses these issues and gets you feeling yourself again.


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