Herb 301 - General Introduction to Chinese Herbal Medicine

Chinese Herbal Medicine (Herb 301) - Lecture 1

General Introduction

• Chinese herbal medicine 中药 (Zhōngyào): Medicinal substances recorded in TCM material medica.
• TCM pharmacology 中药学 (Zhōng yàoxué): Branch of TCM that studies the sourcing, collecting, processing, dispensing, actions, indications, and applications of Chinese herbal medicine.

History & Development of Chinese Herbal Medicine

• Chinese herbal medicines have been in use since ancient times.
• Early humans were hunter-gatherers, relying on hunting and foraging.
• Knowledge of plants and animals' effects on the human body accumulated through trial and error.
• Poisonous substances were used in hunting and eventually in treating ailments.
• Shen Nong 神农: A legendary figure who taught people agriculture. He tasted countless herbal medicines to study their natures and effects, often poisoning himself up to 70 times a day, learning to resolve the toxins, and taught his findings to the people.

Shen Nong Ben Cao Jing 神农本草经

• A book named after Shen Nong, written about 2500 years after his time.
• Records the names, taste, nature, area of origin, and uses of 365 medicines:
  • 252 botanical medicines
  • 67 zoological medicines
  • 46 mineral medicines
• Medicines were categorized into three categories:
  • Upper medicines 上药 (Shàng yào):
    • Non-toxic
    • Nurtures and improves health
  • Middle medicines 中药 (Zhōng yào):
    • May or may not be toxic
    • Nurtures vitality and restores health
  • Lower medicines 下药 (Xià yào):
    • Toxic
    • Only used for extreme cases

Ben Cao Jing Ji Zhu 本草经集注

• Written by Tao HongJing 陶弘景 around 500 CE
• Includes 730 medicines categorized into 7 categories based on their attributes:
  • Jade & stone
  • Plant & wood
  • Insect & animal
  • Fruits
  • Vegetables
  • Miscellaneous/Unknown use

Xin Xiu Ben Cao 新修本草

• Compiled by 24 government officials from 657 CE to 659 CE.
• First state-sponsored compendium of materia medica.
• Includes 844 medicines from various parts of the country.
• Each medicine was described, illustrated, and catalogued in detail.

Jing Shi Zheng Lei Bei Ji Ben Cao 经史证类備急本草

• Written by Tang Shenwei 唐愼微 during the Song Dynasty.
• Includes 1746 medicines and over 3000 formulae.

Ben Cao Gang Mu 本草纲目

• Written by Li Shizhen 李时珍 from 1552 CE to 1578 CE.
• The book has 52 volumes and includes 1892 medicines, 11000 formulae, and 1109 illustrations.
  • 1173 are botanical
  • 444 are zoological
  • 275 are mineral
• Used not only as a pharmacopeia but also as a text on botany, zoology, mineralogy, and metallurgy.
• Translated into many languages and used extensively.

Classification of Chinese Herbal Medicines

• Categorized according to their major functions (e.g., clear heat, cool blood 清热凉血).

Origin of Chinese Herbal Medicine

• Origin refers to the natural habitat or place of production of each CHM.
• Most CHM are plant-based; factors affecting quality include:
  • Soil quality
  • Water quality
  • Local climate
  • Pollution
• Different species of the same genus or family may or may not have the same effect.
• The same species grown in different localities may have differing qualities or effects.
• In ancient practice, TCM relied on gathering CHM from their natural habitat.

Authentic Medicines 道地药材

• CHM of the ideal species, growing in the ideal locality, under the ideal conditions with the highest quality and potency were highly sought after.
• In modern practice, CHM are cultivated and grown using agricultural techniques:
  • Ideal species is ensured via cultivation.
  • Ideal growing conditions are maintained using modern agricultural techniques and equipment.
  • CHM quality is ensured through research and testing.
  • Various quality assurance standards (GMP, GAP, GHP etc.)

Harvest of Chinese Herbal Medicines

• Harvest of CHM is important as the conditions under which they are harvested affects the quality & efficacy of the medicine.
• Conditions include:
  • Time of harvest
  • Season of harvest
  • Method of harvest
• These conditions affect the amount of active ingredient in the final product.
• Harvesting plants:
  • Entire plant: mostly harvested just before blossoming when branches & leaves are full.
  • Leaves: mostly harvested during blossom to full bloom; some leaves are harvested in late fall to early winter.
  • Flowers: harvest is dependent on the type of flower as well as the desired effect.
  • Fruits & seeds: mostly harvested when ripe or just before maturation; some fruits are harvested when unripe.
  • Roots, rhizomes & tubers: mostly harvested in early spring or late fall; some tubers are best harvested in summer.
  • Tree or root bark: mostly harvested between qingming & xiazhi (summer solstice according to lunar calendar); Rou gui (cinnamon bark) is harvested in late fall when essential oils are highest.
• Harvesting animal CHM & minerals
  • Different animal medicines are harvested at different times to maximize efficacy or to facilitate ease of harvesting and/or processing.
  • Mineral medicines generally may be harvested at any time.

Processing of Chinese Herbal Medicine 中药炮制

• After harvesting, the crude herbs are processed into various forms depending on clinical application, storage, prescription, and other such needs.
• The purpose of processing includes:
  • To increase efficacy
  • To reduce or eliminate toxicity or adverse effects
  • To change the action, property or effect
  • For storage & preparation
  • For purification & removal of contaminants
• Methods of processing include:
  • Manual processing
  • Liquid processing
  • Fire/heat processing
  • Liquid & heat processing
  • Special processing methods

Manual Processing

• Removing contaminants & impurities via manual methods like brushing, scraping, picking, sieving etc.

Liquid Processing

• Softening the material or reducing the concentration/contaminants of the material via processing with water or other liquids.
  • Moistening: softening the material or instilling other properties using a small amount of liquid.
  • Rinsing: washing with running water to remove unwanted materials.
  • Solvent refining: used for mineral materials to purify the final product.

Fire/Heat Processing

• Heating the herbs with or without an adjuvant.
  • Stir-baking 炒 Chao:
    • Heating to various degrees of yellowing or browning without any adjuvant.
    • Yellowing helps to release the active ingredients.
    • Carbonizing (until burnt) can resolve toxicity & add an astringent quality.
    • Herbs may be baked with earth or rice to augment SP/ST tonification.
    • Also used to reduce cold nature of certain herbs.
  • Quick-frying 炮 Pao:
    • Heating with high heat until dark brown.
    • Reduces toxicity.
  • Charring/Carbonizing 炭 Tan:
    • Heating herbs until mostly burnt black.
    • Augments hemostatic properties.
  • Roasting 煨 Wei:
    • Wrapping herbs in wet paper or wet flour & placing in hot ashes.
    • Reduces toxicity and/or moderates drastic actions.
  • Stir-baking w/ liquid炙 Zhi:
    • Herb is heated with a liquid adjuvant such as wine, honey, vinegar, ginger juice, saline solution etc. to augment certain effects & reduce adverse effects.
    • Each adjuvant has a specific effect on the properties of the herb:
      • Wine/liquor 酒 Jiu – Augments qi & blood invigorating properties (clear obstruction, alleviate pain).
      • Honey 蜜 Mi – Augments moistening & tonifying properties.
      • Vinegar 醋 Cu – Augments astringent, analgesic, blood invigorating & detoxifying qualities.
      • Ginger juice 姜 Jiang – Protects ST from cold, bitter nature of herbs.
      • Saline solution 盐 Yan – Guides herb action to KD/LJ.
  • Calcination 煅 Duan:
    • Herb is heated with extreme heat – achieved with an oven, torch (direct calcination) or a sealed in a refractory vessel & heated in a kiln/forge (indirect calcination) where the herbs are heated until red hot & allowed to cool.
    • Mineral & shell medicines are calcinated directly with a strong flame or over an open stove.
    • Certain medicines that are light & fluffy are sealed in a refractory vessel & heated.
    • Calcination makes hard mineral & shell herbs brittle & easier to pulverize into powder or for the active ingredients to be released.

Liquid & Heat Processing

• Quenching 蘸 Zhan:
  • Calcinated medicines are quickly immersed in a liquid while still red hot.
  • Makes the material crisp, brittle, easier to process & more effective.
• Scalding 潬 Dan:
  • The herbs are placed in boiling water & quickly removed.
  • Used to remove the outer coating of seeds that have no therapeutic effect & may prevent the release of active ingredients.
  • Also helps pulpy or juicy herbs easier to dry & store.
• Steaming 蒸 Zheng:
  • Medicines are steamed in water or wine vapor.
  • Used to facilitate processing (e.g., softening for cutting) or drying/storing.
  • Also to change the properties & efficacy of the herb.
• Boiling 滚 Gun:
  • Medicines are boiled in water or other liquids such as vinegar or wine.
  • Used to reduce toxicity or drastic/adverse effects or to increase efficacy.

Special Processing Methods

• Include frost-powder making, fermentation, sprouting/germination etc.

Properties & Actions

• 是药三分毒 Shì yào sān fēn dú – All medicines have the potential to heal & to harm.
• Properties of herbs are constant; it must be properly applied in order to heal; otherwise, it will cause harm to the patient.
• Practitioners must know the properties & actions of each herb very well.
• CHM properties & actions are described by 4 major categories:
  • The four natures 四气 Si Qi
  • The five flavors 五味 Wu Wei
  • The four directions 升降浮沉 Sheng Jiang Fu Chen
  • Meridian tropism 归经 Gui Jing

The Four Natures 四气 Si Qi

• Hot 热 Re

• Warm 温 Wen

• Cool 凉 Liang

• Cold 寒 Han

• Hot & warm herbs are used to treat cold conditions – belongs to yang

• Hot & warm refer to their relative natures – hot is stronger than warm

• Usually used to warm interior, expel cold, warm yang, tonify qi

• Cold & cool herbs are used to treat heat conditions – belongs to yin

• Cold & cool refer to their relative natures – cold is stronger than cool

• Usually used to clear heat

The Five Flavors 五味 Wu Wei

• Pungent 辛 Xin:
  • Yang in nature; pertains to LU
  • Disperses, moves qi, activates blood, induces perspiration
  • Often used to release exterior & disperse stagnation
  • Overuse or improper use may lead to exhaustion of qi & yin
• Sweet 甘 Gan:
  • Yang in nature; pertains to SP
  • Tonifies deficiency, harmonizes, stops pain, moistens dryness
  • Often used to strengthen & tonify or to moderate other herbs
  • Overuse or improper use may cause accumulation of dampness
• Bitter 苦 Ku:
  • Yin in nature: pertains to HT
  • Purges & dries – clear heat, dries dampness, descends rebellious qi
  • Often used to treat damp conditions (both cold & heat), to clear heat & purge the bowels
  • Overuse or prolonged use may damage yin over time
• Sour 酸 Suan
  • Yin in nature; pertains to LV
  • Astringes & consolidates
  • Often used to stop sweating, emission, leukorrhea, diarrhea etc.
  • Combined with sweet flavour to produce yin 酸甘化阴
• Salty 咸 Xian:
  • Yin in nature; pertains to KD
  • Descends, softens & dissipates hard masses, purges
  • Often used to treat masses & nodules, constipation
• Bland 淡 Dan:
  • Yang in nature
  • Leeches out dampness by promoting diuresis
• Astringent 涩 Se:
  • Similar to sour
  • Lacks the yin producing property when combined with sweet flavor
  • Used to astringe leaking of fluids

The Four Directions 升降浮沉 Sheng Jiang Fu Chen

• Describes the direction of a medicine’s action.

• The four directions are:

  • Ascending 升 Sheng
  • Descending 降 Jiang
  • Floating 浮 Fu
  • Sinking 沉 Chen

• The direction of the medicine’s action dictates its efficacy for treating certain conditions.

• A medicine’s direction may be modified by processing.

  • Ascending 升 Sheng
    • Moving upwards
    • Has ability to expel wind, raise yang, raise prolapsed organs
  • Descending 降 Jiang
    • Moving downwards
    • Has ability to descend rebellious qi, calm dyspnea, purge downwards
  • Floating 浮 Fu
    • Moving outwards
    • Has ability to promote sweating, scattering cold
  • Sinking 沉 Chen
    • Moving inwards
    • Has ability to anchor ascending yang, calm the mind, extinguish wind

• In general…

  • …medicines with a hot/warm nature or pungent/sweet taste are ascending or floating; pertain to yang – increases yang qi, induces diaphoresis, disperses wind & cold etc.
  • …medicines with cold/cool nature or salty/sour/bitter taste are descending or sinking; pertain to yin – astringe & consolidate, stop coughing/asthma/dyspnea, clear heat, purge bowels etc.
  • …medicines that are physically light (flowers, leaves, branches etc.) are ascending or floating
  • …medicines that are heavy (minerals, shells, seeds etc.) are descending or sinking

• Processing with…

  • …alcohol changes direction to ascending
  • …salt changes direction to descending
  • …ginger changes direction to floating/dispersing
  • …vinegar changes direction to sinking/astringent

Meridian Tropism 归经 Gui Jing

• Refers to the site of action – i.e., which meridian does the medicine affect?
• “Meridian” includes channels, collaterals & zang fu organ.
• Different herbs with similar properties but different meridian tropism will have similar actions but in different parts of the body.
• One herb may act on more than one meridian.
• Categorization of herbs by meridian is based on its effect on zang fu function.
• Herbs w/ effect on respiration, skin & or exterior enter/act on the LU meridian of hand taiyin.
• Herbs w/ effect on the spirit, circulation, psycho-emotional etc. enter/act on HT meridian of hand shaoyin.
• Herbs w/ effect on bowel movement enters/act on LI meridian of hand yangming.
• Herbs w/ effect on urination may enter/act on UB meridian of foot taiyang or KD meridian of foot shaoyin.

Toxicity 毒性

• 是药三分毒 Shì yào sān fēn dú – All medicines have the potential to heal & to harm.
• While all herbs have the potential to be toxic, some are poisonous – especially in raw form
• To reduce the risk of toxicity, the following factors must be kept in mind:
  • Correct dosage
  • Correct processing
  • Correct pairing
  • Herb-drug/herb-herb interactions
  • Correct diagnosis
  • Patient’s constitution
  • Correct application
  • Correct cooking
  • Correct administration

Compatibility

• Refers to the combination of 2 or more herbs to achieve a certain effect
• Used together, herbs may have complicated reactions
• These reactions are summarized as the seven compatibilities:
  • Individual action 单行 Dan Xing
  • Mutual reinforcement 相需 Xiang Xu
  • Mutual assistance 相使 Xiang Shi
  • Mutual restraint 相偎 Xiang Wei
  • Mutual detoxification 相杀 Xiang Sha
  • Mutual inhibition 相恶 Xiang Wu
  • Mutual antagonism 相反 Xiang Fan

Individual Action 单行 Dan Xing

• Use of a single herb to treat a mild or simple condition.
• Combination of herbs that have no effect on each other’s actions.
• E.g., Sheng Jiang 生姜 (Fresh ginger) to treat nausea/vomiting

Mutual Reinforcement 相需 Xiang Xu

• Combination of 2 or more herbs with similar actions/properties to reinforce each other synergistically.
• E.g., Tao Ren 桃仁 + Hong Hua 红花 to invigorate blood, resolve stasis
• E.g., Dang Gui 当归 + Huang Qi 黄芪 to tonify qi & blood

Mutual Assistance 相使 Xiang Shi

• Combination of 2 or more herbs w/ similar properties in which 1 is the primary herb & all others assist the primary herb’s functions.
• In practice, very similar to mutual reinforcement but lacks synergistic action.
• In mutual reinforcement, the resulting effect from combination is more than just the sum of the herbs; the combinations are specific.
• In mutual assistance, the herbs simply work together; combinations are non-specific.
• E.g., Huang Qi 黄芪 + Fu Ling 茯苓 – Huang Qi tonifies qi & is primary; Fu Ling leaches out dampness & strengthens the SP.

Mutual Restraint 相偎 Xiang Wei

• Combination of 2 of more herbs that restrain & weaken each other’s actions (reduce toxicity or adverse effect).
• E.g., Sheng Jiang 生姜 used to remove toxicity of Ban Xia 半夏 & Nan Xing 南星

Mutual Detoxification 相杀 Xiang Sha

• Combination of 2 or more herbs reduces or eliminates toxicity or adverse effect of each other.
• Same as mutual restraint.

Mutual Inhibition 相恶 Xiang Wu

• Combination of 2 or more herbs in which they mutually inhibit their actions.
• E.g., Sheng Jiang 生姜 + Huang Qin 黄芩 – Sheng Jiang warms LU & ST while Huang Qin cools LU & ST.

Mutual Antagonism 相反 Xiang Fan

• Combination of 2 or more herbs reinforces or creates new toxicity or adverse effects.
• E.g., Yan Hu Suo 延胡索 increases toxicity of Ma Qian Zi 马钱子
• E.g., Zhu Sha 朱砂 combined with Kun Bu 昆布 – Iodine from Kun Bu reacts with the mercury in Zhu Sha to produce mercuric iodide, increasing bioavailability of mercury leading to mercury poisoning.

18 Antagonisms 十八反 & 19 Restraints 十九畏

• First described in the Song, Jin & Yuan Dynasties, these are combinations of herbs that are traditionally believed to cause adverse effects.
• 18 antagonisms:
  • Wu Tou 乌头 antagonizes Ban Xia 半夏, Gua Lou 瓜蒌, Bei Mu 贝母, Bai Lian 白蔹 & Bai Ji 白芨
  • Gan Cao 甘草 antagonizes Hai Zao 海藻, Da Ji 大戟, Gan Sui 甘遂 & Yuan Hua 芫花
  • Li Lu 藜芦 antagonizes Ren Shen 人参, Sha Shen 沙参, Xuan Shen 玄参, Dan Shen 丹参, Xi Xin 细辛, Shao Yao 芍药
• 19 Restraints:
  • Liu Huang 硫磺 restrains Pu Xiao 朴硝
  • Ya Xiao 牙硝 restrains San Leng 三棱
  • Shui Yin 水银 restrains Pi Shuang 砒霜
  • Chuan Wu 川乌, Cao Wu 草乌 restrains Xi Jiao 犀角
  • Lang Du 狼毒 restrains Mi Tuo Seng 密陀僧
  • Ren Shen 人参 restrains Wu Ling Zhi 五灵脂
  • Ba Dou 巴豆 restrains Qian Niu 牵牛
  • Guan Gui 官桂 restrains Chi Shi Zhi 赤石脂
  • Ding Xiang 丁香 restrains Yu Jin 郁金

Contraindications

• Pregnancy – certain herbs should be used with caution or avoided completely to prevent harm to the fetus & the mother
• Herbs contraindicated for pregnancy usually have a drastic action (qi/blood moving, purging etc.) or are toxic
• Prohibited herbs include: Ma Qian Zi 马钱子, Chuan Wu 川乌, Cao Wu 草乌, Ban Mao 斑蝥, Ba Dou 巴豆, Shui Zhi 水蛭, Da Ji 大戟, San Leng 三棱, E Zhu 莪术 etc.
• Herbs that may be used with caution include: Niu Xi 牛膝, Chuan Xiong 川芎, Hong Hua 红花, Tao Ren 桃仁, Jiang Huang 姜黄, Zhi Shi 枳实, Zhi Ke 枳壳, Da Huang 大黄, Fan Xie Ye 番泻叶 etc.

Dietary Restrictions

• Treatment with herbal medicine is more effective when combined with dietary changes
• Certain foods may worsen the condition & act contrary to the action of the herbs
• Raw & cold foods should be avoided by patients with a cold condition
• Spicy, hot & greasy foods should be avoided by patients with a heat condition
• Alcohol, garlic, hot peppers etc. should be avoided by patients with dizziness, insomnia & irritability
• Fried, greasy, oily, sweet, sticky, raw, cold, fishy, stimulating & other foods that are difficult to digest should be avoided by patients with a SP/ST deficiency
• Shellfish & scale-less fish should be avoided by patients with skin & pruritic conditions
• In general:
  • SP/ST must be protected to ensure herbal medicine is properly absorbed
  • Foods that aggravate the syndrome should be avoided
  • Foods that have a mutual inhibitive or mutual antagonistic property with the herbs being administered should be avoided

Application & Effects of Chinese Herbal Medicine

8 Treatment Methods of TCM 八法 Ba Fa:

• Diaphoresis 汗法 Han Fa – Induce sweating
• Emesis 吐法 Tu Fa – Induce vomiting
• Purgation 下法 Xia Fa – Draining down (induce bowel movement)
• Harmonization 和法 He Fa – Harmonizing (Shaoyang etc.)
• Warming 温法 Wen Fa – Warming (dispel cold, warm yang)
• Clearing 清法 Qing Fa – Cooling (clear heat)
• Tonifying 补法 Bu Fa – Strengthening, supplementing
• Reducing 消法 Xiao Fa – Reducing, get rid of pathogens

Tonifying 补 Bu

• Tonify 补 Bu – qi, yang
• Nourish 养 Yang – yin, blood, fluids
• Generate 生 Sheng – fluids (jin ye)

Reducing 泻 Xie

• Expel 祛 Qu – wind, cold
• Dissipate 消 Xiao – accumulations/masses
• Eliminate 除 Chu – dampness, phlegm
• Break 破 Po – blood stasis
• Eject 驱 Qu – parasites
• Dry 燥 – dampness
• Release 解 Jie – exterior pathogens
• Benefit/Disinhibit 利 Li – fluids, qi, blood, dampness
• Clear 清 Qing – heat, summer heat
• Expel/Discharge 排 Pai – phlegm, pus, stasis, stones, water etc.
• Cool 凉 Liang – blood heat
• Purge 下 Xia – pass through the bowels
• Scatter 散 San - cold
• Drastic purgation/attack 攻 Gong – Forcefully expel pathogens

Other Methods

• Regulate 理 Li – qi, blood
• Transform 化 Hua – dampness, phlegm
• Kill 杀 – parasites, worms
• Brighten the eyes 明目 Ming Mu – improve vision, benefit the eyes
• Consolidate/bind 固 Gu – essence, exterior
• Astringe 敛 Lian – restrain/astringe LU, sweating

Structure of a Formula

• Emperor 君 Jun: Main herb that provides the primary function – directly addresses the syndrome/treatment principle; AKA Chief/monarch/sovereign/king
• Minister 臣 Chen: Secondary herb(s) that assists the main herb or addresses secondary syndrome/treatment principles; AKA Deputy/associate
• Adjuvant 佐 Zuo: Tertiary herb(s) that provide support to the main & secondary herbs; AKA Assistant
• Envoy 使 Shi: Harmonize the formula & guide the action

Dosage

• Traditionally, dosage was measured in Chinese units Jin, Liang, Qian, Fen, Li.
• In modern practice, dosage is measured in grams.
• Standard dosage for most herbs is 6g – 9g.
• Dosage is dictated by:
  • Properties of the herb
  • Application
  • Patient’s condition
  • Geographical considerations

Properties of the Herb

• Refers to the actions & nature of the herb being used
• Safe herb with mild action have a wider range of dosage
• Drastic herbs with strong action, extreme natures or toxicity are limited to a small dosage range
• Herbs that are dense (minerals & shells) are used in high dosage
• High-quality herbs require less amount to achieve therapeutic effect; low-quality herbs require more
• Fresh herbs (not thoroughly dried) require a very large dose (double or more)

Application

• Compatibility, form & purpose of the herbs affects the dosage
• Used alone, a single herb should have a higher dosage than when used in a formula with other herbs
• Within one formula, the dose of the primary herb is usually higher than the other herbs
• The form of administration changes the dosage – higher dosage for decoction, lower dose for pill or powder form
• Purpose of the herbs – the same herb prescribed in different dosages will have different effects

Patient’s Condition

• Take into consideration the condition, constitution & age of the patient
• Severe, persistent or acute conditions should be treated with a higher dose
• Mild or chronic condition should be treated with a smaller dose
• Patients w/ strong constitution or young patients may take a higher dose
• Children, elderly & patients w/ weak constitution should take a smaller dose
• Children 6 – 12 should take half of adult dose; children under 6 should take a quarter of adult dose; infants should take a much smaller dose

Geographical Considerations

• Weather & climate affects dosage
• Patients in hot climates tend to sweat more; diaphoretics should be used in smaller dosage (& higher in cold climates)
• Patients in damp/humid climates tend to accumulate more dampness; herbs that are aromatic & dry dampness should be used in larger amounts while sticky/cloying herbs should only be used when necessary
• Patients in cold climates tend to lack yang qi; warming herbs may be used in larger amounts while cooling/heat clearing herbs should only be used when necessary
• Patients in dry/arid climates tend to lack fluids; moistening herbs should be used in larger amounts while drying herbs should only be used when necessary

Administration of Chinese Herbal Medicine

• Most common is oral administration; however, there are other routes of administration both traditional & modern:
  • Cutaneous
  • Rectal
  • Nasal/inhalation
  • Vaginal
  • Sublingual
  • Intravenous injection
  • Intramuscular injection
  • Subcutaneous injection
  • Acupoint injection
• Different tissues have different sensitivity & absorption; the route of administration can affect actions of the herbs as well as rate & quantity of absorption
• Boiling processed & dried herbs in water & taking oral is the most conventional method of administration; other methods are not commonly used in Canada

Method of Decoction

• Decoction vessel & all utensils should be made of chemically inert materials – glass/ceramic is most ideal; stainless steel is ok; avoid cast iron, copper, aluminum, zinc pots/utensils
• Water used for decoction should be clean & free of contaminants & excessive dissolved minerals – traditionally, water used for decoction was thought to be of utmost importance; different types of water had different applications
• The amount of water added to the dried herbs should take into account the absorption of the water
• Prior to decocting, herbs should be soaked in cold water for about 30 mins
• After soaking, bring to rolling boil on high heat, reduce heat to slow boil/simmer
• Allow to simmer for 20 – 40 mins
• Strain herb juice out
• Add water & boil a second time (no need to soak again)
• Strain herb juice from second boiling & mix with first boiling
• May be boiled a third time if necessary
• Herb dredges may be squeezed out to extract as many active ingredients as possible
• Boiling time & temperature depends on the nature of herbs – light, aromatic or pungent herbs should be boiled at a higher temperature for a shorter period while heavy, bland herbs should be boiled at a lower temperature for a longer period of time
• Herbs with active ingredients that are difficult to extract & are not sensitive to overheating need to be decocted first 先煎
• Animal horns, shells, certain minerals need to be boiled for 30 mins to 1 hour before the other herbs
• Some herbs like Ma Huang, Chuan Wu, Cao Wu, Fu Zi need to be decocted first to eliminate toxicity
• Herbs with volatile oils or heat-sensitive active ingredients should be added to the decoction later & boiled for a short period of time
• Herbs that are light or have small hairs that are difficult to boil/strain should be wrapped before boiling
• Herbs that are valuable & prescribed in small amounts should be decocted & administered separately
• Sticky, glue-form herbs should be melted in hot water or herb juice
• Herbs that dissolve easily in water should be dissolved into the herb juice after decoction
• Most herbal decoctions should be taken warm
• Herbal decoctions are generally taken twice a day
• The timing of the administration depends on the condition of the patient