Contraindication of drugs includes contraindication of drugs incompatibility , contraindication of drugs in pregnancy and contraindication of foods in drugs' taking . Contraindication of drugs in pregnancy and contraindication of foods in drugs' taking will be discussed here mainly .

(1).Contraindication of Drugs in Pregnancy

A.Outline The drugs which are harmful for pregnancy can be divided into two kinds , that is , the drugs contraindicated and those used with caution .

The drugs contraindicated are mostly the drugs with stronger toxicity or those with more violent effects . The drugs used with caution are mostly the drugs with violent effects or those with mild toxicity .

The drugs contraindicated can not be used absolutely ; the drugs used with caution must be used according to the gravida's condition properly , but if it is not necessary , usage of these drugs must be avoided as far as possible.

B.Principle The drugs contraindicated and those used with caution are mostly toxic , biological activity of these drugs is stronger , and they can cause contraction of the smooth muscle of the uterus and violent change of bloodflow of the uterus , resulting in abortion or premature labour , or being harmful for development of the fetus .

(2).Contraindication of Foods in Drugs' Taking

A.Outline That the certain foods are prohibited to be eaten in the time when drugs are taken is called contraindication of foods.

B.Principle Certain foods can aggravate diseases or counteract effects of drugs , therefore , these foods must be prohibited to be eaten.

The raw , cold-natured , greasy , indigestible or stimulant foods influence digestion and absorption , therefore , these foods are unsuitable to be eaten in the time when drugs are taken.

The acrid and oily foods can increase energy metabolic rate and heat production of organism , it aggravating heat-natured diseases . Therefore , these foods are unsuitable to be eaten by the patients wiht heat-natured diseases.

The raw and cold-natured foods can decrease energy metabolic rate and heat production of organism , it aggravating cold-natured diseases . Therefore , these foods are unsuitable to be eaten by the patients with cold-natured diseases.

For the patients with carbuncle , tumescence , sore and skin disease , immunity of the organisms is hyperactive . When the patients eat fish , shrimp , crab and others , allergic reaction occurring after heteroprotein's entering body aggravates the diseases. Therefore , these foods are unsuitable to be eaten by the patients with these diseases.

[3].Classification of Drugs

(1).Drugs for Expelling Superficial Evils

A.Outline The drugs which can disperse superficial evils and relieve superficies-syndrome are called drugs for expelling superficial evils.

Among drugs of this kind , the drugs which are acrid and warm , have the effect of dispersing wind-cold evil , and are applicable to superficies-syndrome due to wind-cold evil are called drugs with acrid flavour and warm nature for expelling superficial evils , the drugs which are acrid and cool , have the effect of dispersing wind-heat evil , and are applicable to superficies-syndrome due to wind-heat evil are called drugs with acrid flavour and cool nature for expelling superficial evils.

In addition , a part of drugs for expelling superficial evils also have the effects of leting out measles , subsiding swellings , dispersing sores and others , and these drugs are used in the patients of appearance early and disturbance of appearance of measles ; those of superficies-syndrome with unfestered sores , and redness , tumescence , pain and edema , as well as aversion to cold , and fever ; and those with wind-wetness evil in the superficies and pain of the trunk and extreminties.

B.Principle Superficies-syndrome is a syndrome occurring in the initial stage o the infectious diseases . The main manifestations of pathological responses of superficies-syndrome are changes of relaxation or contraction of the blood vessels in the body surface , the mucous membrane of the respiratory tract , and the brain ; and disturbance of the heat-regulating center caused by effect of endogenous pyrogen.

The drugs for expelling superficial evils have the effects of regulating bloodflow of the body surface , the mucous membrane of the respiratory tract , and the brain ; promoting sweat , relieving fever ; resisting bacteria and viruses ; and others.

The drugs with acrid flavour and warm nature for expelling superficial evils contain volatile oils , alkaloids and other components , and these drugs have the effects of exciting the central nervous system , exciting the sympathetic nervous system , tonicizing the heart , dilating blood vessels of the skin , stimulating secretion of the sweat glands , promoting diuresis , inhibiting allergic reaction , and others.

The drugs with acrid flavour and cool nature for expelling superficial evils contain volatile oils , glycosides , alkaloids and other components . The molecules of their chemical components mostly carry hydroxyl or double bond , and they have the effects of resisting bacteria and viruses , relieving fever, promoting sedation , lowering blood pressure and others.

(2).Drugs for Purging

A.Outline The drugs which can cause diarrhea or lubricate the large intestine and promote defecation are called drugs for purging.

The drugs for purging can be divided into three kinds, that is, drugs for purging to eliminate evils,drugs for lubricating intestinal tract and promoting defecation,and drugs for potently purging and expelling water.

B.Principle The drugs for purging have the effect of promoting defecation.

Among the drugs for purging to eliminate evils , Radix et Rhizoma Rhei , Folium Cassiae and Aloe contain derivatives of anthracene glycoside , and these drugs have the effects of inccreasing tension of the large intestine to promote its movement , inhibiting activity of sodium pump in cell membrane of epithelium of the large intestine , and making water be detained in the intestinal canal to promote defecation . The effect of purging of these drugs does not influence absorption of nutritional materials in the small intestine . Mirabilitum contains sodium sulfate . Ions of sulphuric acid radicle are not absorbed easily inside the intesine , and the intestinal contents which keep hyperosmotic state prevent water being absorbed in the intestinal tract , even attract water inside body to the intestinal canal to increase capacity of the intestinal contents and stimulate the intestinal wall , to strengthen movement of the intestinal tract , thus causing diarrhea . Radix et Rhizoma Rhei also have the effects of resisting bacteria , lowering blood pressure , lowering cholesterol , stopping bleeding , promoting choleresis and cholerrhagia , promoting diuresis , resisting tumor , and others , therefore it can relieve the various symptoms of sthenia-syndrome.

The effect of demulcently relaxing the bowels of the drugs for lubricating intestinal tract and promoting defecation is caused by a large amount of fatty oil contained by these drugs.

The drugs for potently purging and expelling water have the effects of purging and promoting diuresis . Drugs of this kind mostly contain the components which stimulate the mucous membrane strongly , and these components mostly exist in fatty components . These drugs can cause hypermotility and hypersecretion of the entire digestive tract to result in watery diarrhea and influence absorption of nutritional materials in the small intestine . Drugs of this kind also have the effects of strengthening activity of the kidneys and promoting diuresis to eliminate edema and others.