Herbs that relieve food stagnation are able to promote digestion and dissolve food accumulation. Although food stagnation is not commonly seen nowadays in the developed countries because of the influence of healthy dietary principles, it may still happen in certain situations. First of all, in infants, since the Spleen and Stomach are not fully developed and the parents may lack experience or knowledge of the best diet for children, the child may suffer from indigestion. Secondly, in people with a weak constitution or who suffer from chronic disease, because the functions of the Spleen and Stomach are insufficient, food may tend to stagnate in the Middle Jiao. Thirdly, in elderly people, since the digestion slows with age, indigestion may easily happen. Acute or Excess cases of food stagnation may also occur when on holiday if the diet is changed significantly or the person overindulges.

Food stagnation is caused by the obstruction of the Qi in the Middle Jiao. The main symptoms are fullness in the stomach, belching, nausea, vomiting with a foul smell, distending pain in the abdomen and constipation or diarrhea. The tongue body is normal or slightly red and the coating is thick, white or slightly yellow. The pulse is slippery, forceful and rapid. In chronic cases of food stagnation, especially in those people with Spleen and Stomach deficiency, symptoms of Qi and Blood deficiency may appear. In children, it may affect their general health and development.

Herbs that relieve food stagnation should be used with caution because they can digest, dissolve and transport food; therefore they may injure the Stomach, Spleen, Qi and Blood too. They are generally used for only a short treatment course. When the accumulated food has been digested, these herbs should be stopped. In people who suffer from indigestion with deficiency of the Spleen and Stomach, these herbs should be used together with herbs that tonify the Spleen and Stomach. In addition, these herbs are normally not used in large dosages, and are often used together with other herbs to enhance the effect, such as herbs that promote the Qi movement, eliminate Dampness or clear Heat in the Middle Jiao. For patients who have a weakness of the Spleen and Stomach, herbs that are slightly warm in temperature are often used to warm the Middle Jiao and accelerate the function of these organs.

These three herbs are often used together because they have different functions and can enhance each other’s therapeutic effects. Mai Ya is sweet and neutral, and enters the Spleen and Stomach meridians; it especially aids the digestion of wheat, rice and fruits. Shen Qu is pungent, sweet and warm, and enters the Spleen and Stomach meridians; it particularly aids the digestion of cereals and dispels the effects of alcohol. Shan Zha is sour, sweet and slightly warm, and enters the Spleen, Stomach and Liver meridians; it especially aids the digestion of meat, fat and milk. Because in most cases of food stagnation these foods and drinks are all involved, the three herbs are often used together.

Shen Qu and Gu Ya both can aid the digestion of cereals and reduce the food stagnation, but Shen Qu is stronger than Gu Ya in action. Shen Qu is pungent, sweet and warm and is able to promote the Qi movement, soothe the Stomach-Qi, and aid the digestion of starchy foods which are heavy to the stomach, such as grains and brown bread. It is effective for reducing distension and heavy sensations in the stomach. Gu Ya is much gentler in action than Shen Qu; however, as it has tonifying ability, it can be used for a long time.