Traditional Chinese Medicine/Herb To Herb Interactions

In Traditional Chinese Medicine, herb-to-herb interactions have been known for a long time, and include both synergistic as well as antagonistic interactions.

Synergistic Interactions
Synergistic Interactions are of the following two types:


 * Mutual Accentuation (Xiang Xu) - 相须
 * Mutual Enhancement (Xiang Shi) - 相使

Mutual Accentuation
In Mutual Accentuation, two herbs with similar functions are used together to increase their therapeutic effect. Examples include:
 * 1) Jing Jie (荆芥) with Fang Feng (防风) to expel wind and release the exterior
 * 2) Jin Yin Hua (金银花) with Lian Qiao (连翘) to reduce heat-toxin
 * 3) Da Huang (大黄) with Mang Xiao (芒硝) to promote bowel movement

Mutual Enhancement
In Mutual Enhancement, two herbs with different functions are used. The first directly targets the pathological condition, and the second increases the therapeutic effect of the first. Examples include:


 * 1) Zhi Mu (知母) with Huang Bai (黄柏), where Zhi Mu nourishes yin of the kidney and clears heat in the Lower-Jiao, while Huang Bai reduces empty-heat in the Lower-Jiao and is able to enhance the function of Zhi Mu.
 * 2) Fu Zi (附子) with Zhi Gan Cao (炙甘草), where sweet Gan Cao can moderate the speed of hot Fu Zi.
 * 3) Da Huang (大黄) with Zhi Gan Cao (炙甘草), where sweet Gan Cao can reduce the harsh purging effect of Da Huang.

Antagonistic Interactions
Antagonistic Interactions are of the following four types:


 * Mutual Counteraction (Xiang Wei) - 相畏
 * Mutual Suppression (Xiang Sha) - 相杀
 * Mutual Antagonism (Xiang Wu) - 相恶
 * Mutual Incompatibility (Xiang Fan) - 相反

Mutual Counteraction
In Mutual Counteraction, the characteristic side effects or toxicity of the first herb can be minimized or neutralized by the second herb. An example is:


 * 1) Ban Xia (半夏) with Sheng Jiang (生姜), where the toxic effects of Ban Xia can be reduced by Sheng Jiang.

Mutual Suppression
In Mutual Suppression, the first herb suppresses or minimizes the toxicity of the second herb. Examples include:


 * 1) Lv Dou (绿豆) with Ba Dou (巴豆), where Lv Dou can reduce the toxicity of Ba Dou.
 * 2) Ge Hua (葛花) with alcohol (酒), where Ge Hua can reduce the toxicity of ethanol.

Mutual Antagonism
The following is the classic list of eighteen substances that exhibit Mutual Antagonism to each other. For example, the effects of Ding Xiang will be countered by Yu Jin, and the herbs should not be taken together, although both are very common herbs.

Mutual Incompatibility
The following is the classic list of nineteeen substances that are incompatible with each other, and using them together can have dangerous results:


 * Gan Cao (甘草) is incompatible with the following:


 * All forms of Wu Tou (乌头), including Chuan Wu (川乌), Cao Wu (草乌) and Fu Zi (附子), are incompatible with the following:


 * Li Lu (藜芦) is incompatible with the following:

Single Effect
Although rather rare, some herbs may be used alone (单行) because they have reasonably balanced properties and functions. These include
 * Ren Shen
 * Dan Shen
 * Dang Gui
 * Gan Cao

Herbs That Are Used With Caution During Pregnancy
Ref: http://apps.who.int/medicinedocs/documents/s17556en/s17556en.pdf