Constipation can be divided into Deficiency and Excess types, which are often caused by insufficient fluid in the intestines or obstruction of the Qi with Heat or Cold. It is often related to bad dietary habits, changes of diet, usage of certain medicines, weakness of the Yin and Blood in elderly people, after giving birth, or it may be habitual constipation. The main symptoms are constipation or difficult bowel movement, abdominal distension, fullness of the stomach and dryness in the mouth. The tongue is slightly purple; the coating is dry, thick, white or yellow in color. The pulse is deep, wiry or deep and thready.

The obstruction often has an acute onset. It can be caused by accumulation of feces, Qi, Blood, Heat, Fire-toxin or Cold in the intestine as well as in the abdomen. The main symptoms are severe abdominal pain, cramp, distension, irregular bowel movement or no bowel movement, fullness of the stomach, nausea, vomiting, reduced appetite, dryness in the mouth, thirst and irritability. The tongue body is red with a dry, yellow or white coating and the pulse is deep, slippery and wiry. This syndrome can be seen in severe constipation, initial stages of simple or partial intestinal obstruction, intestinal adhesion, intussusception and other acute abdominal syndromes.

In the syndrome of Fire-toxin accumulation, when the Fire-toxin has not yet accumulated over a long time and the Blood is not strongly disturbed, the main symptoms are fever, irritability, severe thirst, pain and distension in the abdomen (such as in the initial stage of acute appendicitis), acute pancreatitis, acute cholecystitis, hepatitis and ulcer perforation with mild infection and inflammation. Most of the herbs to treat this disorder are cold in temperature. They can purge the accumulation, drain Excessive-Heat and cool the Blood. They are often used to treat Fire-toxin accumulation in the body. The downward-draining action can move the bowels, and can therefore eliminate Heat and Fire-toxin from the body.

When the water metabolism is disturbed, water can accumulate in certain places; this is seen in hydrothorax and ascites. This disorder brings about symptoms such as tightness in the chest, shortness of breath and distension of the abdomen. It can also relieve generalized edema. There are herbs which have both cathartic and diuretic effects and can drive out the water and relieve the symptoms.

Most of the herbs that drain downward are bitter and cold because most of the syndromes they treat have substantial accumulation with Excessive-Heat in the intestines. The Heat comes from various sources. First of all, the Stomach and Large Intestine are called the ‘family of Bright Yang (Yang Ming)’ where Yang and Qi are abundant. Secondly, the Stomach and Large Intestine are the most important organs for transporting food and feces, so the Yang and Qi are active all the time and also produce heat. Thirdly, when there is obstruction in the intestines, as in constipation, the Qi is easily obstructed and Heat will be produced; moreover, most infections produce Heat or Fire-toxin and the accumulation of toxic substances also produces heat when the functions of the liver and kidney are impaired.

Bitterness and Cold both move downwards; Cold, of course, can drain Heat and Fire-toxin. The commonly used bitter and cold herbs are Da Huang ( Rhei rhizoma), Lu Hui ( Aloe folii extractus), Qian Niu Zi ( Pharbitidis semen)*, Gan Sui ( Euphorbiae kansui radix)*, ( Knoxiae radix)*, Shang Lu ( Phytolaccae radix)* and Ting Li Zi ( Lepidii/Descurainiae semen).

Herbs with a salty taste move downwards; they are also able to generate the Body Fluids and soften hardness. A downward-draining substance with a salty and cold property is especially suitable for treating constipation when the feces are very dry and hard. An example is Mang Xiao ( Natrii sulfas).

Herbs with a sweet taste are normally seen among the moist laxatives. Sweetness can harmonize the functions of the intestines and alleviate cramp; examples include Huo Ma Ren ( Cannabis semen) and Yu Li Ren ( Pruni semen). Where harsh purgatives or herbs that drive out water possess a sweet taste, this may relatively reduce the speed of the action and reduce the harsh property. Herbs with this characteristic include Fan Xie Ye ( Sennae folium) and Huo Ma Ren.

Seeds or nuts are gentle laxatives. As they contain lipids, they can lubricate the intestines and ease the expulsion of stools. They are especially suitable for habitual constipation and constipation caused by weakness of Yin and Blood. Commonly used herbs are Huo Ma Ren, Yu Li Ren, Xing Ren ( Armeniacae semen) and Tao Ren ( Persicae semen).