Toxicity refers to a harmful effect of a medicinal herb to the human body, a poisonous medicinal material being known as a toxin. The medicinal herbs drastic or poisonous in nature, if used improperly, can do harm to the body for the light and can cause death for the severe. In order to ensure safety in the use of medicinal herbs, their toxicity must be thoroughly understood.
Dosage of poisonous medicinal herbs in the treatment is close or same to poisoning dosage, so the safety margin is small and poisoning is easily resulted. Whereas the dosage of non-poisonous medicinal herbs in treatment is much farther from the poisoning dosage, and the safety margin is also larger. But it is not absolute whether they can result in poisonous reaction or not. In order to ensure the safety in administration of medicinal herbs and bring therapeutic effects into play and avoid poisonous reaction, you should pay attention to the follows as you use the poisonous ones.
1.4.1 Strictly processing
The toxicity of poisonous Chinese medicinal herbs can be reduced by being processed. Therefore, you must strictly follow the process rules of preparing raw medicinal materials. For instance, Badou ( Fructus Crotonis ), a kind of drastic purgatives that is poisonous in nature, easily results in poisoning if not prepared into Badoushuang (Semen Crotonis Pulveratum ) which is taken orally. After Fuzi (Radix Aconiti) is prepared through soaking, its toxicity decreases and it can be widely used and mean-while does not easily cause poisoning.
1.4.2 Control of dosage
Poisonous occurrence is related to the excessive dosage of administration. So the dosage of toxic medicinal herbs, especially those with extreme toxin, must be strictly controlled and their dosage can not be increased at will. They should be used from small dose and increased according to patient's condition after they are taken. But they are not used for a long time in order to prevent the body from being poisoned due to accumulation of toxicity.
1.4.3 Notes of application
The poisonous medicinal herbs, their toxicity being extreme or mild, are not used in completely common way. Some can be applied exteriorly and can't be taken orally, such as Shengyao (Coarsely prepared mercuric oxide) and Maoliang (Herba et Radix Ranunculi ); some can b added to pill or bolus and powder, not to decoction, such as Chansu (Venenum Bufonis ) and Banmao (Mylabris); some cannot be prepared into pill or tablet with wine, such as Chuanwu (Radix Aconiti). If some are put into a complex prescription, their toxicity is weakened and if a single dose is taken orally, the toxicity is severer. For instance, Fuzi ( Radix Aconiti Lateralis Praeparata ) has an extreme toxin if taken singly and its toxicity will decrease if taken with Shengjiang (Rhizoma Zingiberis Recens ).
