Oedema is characterised by over-retention of water in different parts of the body. Water is essential for life and for all the physiological processes in the body, however if it accumulates then it becomes 'pathogenic ' or 'disease causing '. So, we can differentiate between water that is good for us, 'physiological water', and water that is bad for us, 'pathogenic water'. It is all water, but depending on the amount and location of the water, it is either good or bad.

Oedema may be generalised or localised. It may for example affect the face, or the abdomen, or the legs. It may be hot or cold to touch. It may have started very suddenly, or it may have a gradual onset over many years. When pressure is applied on the oedematous area then it may leave a 'pitting' behind where the finger was. There may be ulcers or boils, or pimples present. All these aspects are important in forming a diagnosis in Chinese medicine.

Taking a detailed history of the illness is important in order to form a diagnosis, look for a possible cause, and to formulate a treatment plan. Depending on the type and severity of the oedema, treatment maybe over many months or it may respond quickly.