Instead of isolating single active compounds to treat a disease, Chinese medicine practitioners intentionally combine single herbs into formulae to suit each patient based on their individual symptoms.
The knowledge of combining single herbs into formulas was first recorded in Shennong Bencao Jing, a classic book of Chinese herbal medicine written over 2,000 years ago.
There are 8,980 herbs compiled into Zhong Hua Ben Cao (Chinese Materia Medica 1999) and 1,444 Chinese herbal formulae collected in 2010 edition of the Chinese Pharmacopoeia.
Chinese herbal medicine formulae are composed according to the following principles:
- Single Effect: using only one medicinal substance to treat a patient;
- Mutual Accentuation: the combination of two herbs with similar functions to enhance their combined effects;
- Mutual Enhancement: the combination of two or more herbs with different actions in which one of the substances enhances the effect of the other;
- Mutual counteraction and suppression: a combination in which the toxicity or side effects of one herb are reduced or eliminated by another;
Some herbs are never used together in the same formula because of:
- Mutual antagonism: the ability of two substances to minimise each herb’s positive effects;
- Mutual incompatibility: the combination of two substances causes side effects or toxicity which would not be caused by any one of the substances if used alone.
Each formula is also guided by the “Jun-Chen-Zuo-Shi” principle of having:
- Chief herbs that provide the main therapeutic effect;
- Deputy herbs that enhance or assist the therapeutic actions of the chief;
- Assistant herbs that provide one or more of the following functions: treating accompanying symptoms, moderating the harshness or toxicity of the primary substances, or modifying the thermal properties of the formula; and
- Envoy herbs that either guide the other herbs in the formula to a specific channel or organ, or exert a harmonising influence over the whole formula.
The individual herbs and dosages of each formula are composed for each person, and further modified after each course, to address specific symptoms and to reduce any side-effects.
The end result is a form of highly personalised medicine.