Purgative herbs either stimulate or lubricate the large intestine to promote bowel movement. They are mainly indicated in constipation. Through the function of purgation, impacted feces and fluid remaining in the intestines are discharged, pathogenic heat or cold dispelled, and edema relieved. Based on their functions and indications, the herbs are divided into three classes: herbs that purge feces, herbs that lubricate the intestines, and herbs that transform water.
Notes on application:
(1)When interior syndrome occurs with exterior syndrome, these herbs are used in combination with those that release exterior syndrome. Alternatively, herbs that release the exterior are given first, followed by herbs that treat interior syndrome.
(2)When body resistance (anti-pathogenic factor) is weak, these herbs are used with tonifying herbs.
(3)These herbs should be used with caution during weakness of the body due to chronic disease, and during menstruation and pregnancy and after delivery.
(4)Since the herbs induce diarrhea, they should be discontinued once the bowel movement has normalized.
Prescriptions which have the functions of purging heat, dispelling cold, and removing water retention, and are used in the treatment of interior excess syndromes, are called “Purgative Prescriptions.” Interior syndrome of the excess type may be caused by the accumulation of heat, cold, dryness, or fluid. Therefore, purgative prescriptions can be divided into four categories:
(1)Purgative Prescriptions with composition of a cold nature: They relax the bowels and purge heat, and are used to treat constipation due to heat accumulation.
(2)Purgative Prescriptions with composition of a warm nature: They dispel cold and are mainly used for treating constipation due to cold accumulation.
(3)Laxatives: They relax the bowels to relieve constipation, and are applied in cases of intestinal dryness induced by deficiency of body fluids.
(4)Purgative Prescriptions with composition for removing water retention: They direct retained water downward for removal from the body and are used for treating ascites and general edema.
Purgative Prescriptions are likely to impair the middle Jiao, consume body fluid, affect blood flow, and cause abortion, and thus should be discontinued immediately once the expected results have been achieved. They should be applied with great caution or contraindicated in the aged, the weak, those with blood deficiency from constitutional weakness or in recovery post-illness, or women during menstruation or pregnancy.
Purgative Herbs
Herbs that purge cause diarrhea. They are bitter and cold in property, and function to reduce fire and promote bowel movement. They are indicated in retention of feces due to accumulation of excessive heat in the stomach and intestines. They are often used with herbs promoting Qi circulation and with herbs that clear heat and drain feces downward.
Rhubarb (Da Huang, 大黄)
Pharmaceutical Name: Radix et Rhizoma rhei
Part Used: Root or rhizome
Properties: Bitter and cold
Channel Tropism: Spleen, stomach, large intestine, and liver
| Functions: | (a) | To promote bowel movement; |
| (b) | To reduce fire and release toxins; | |
| (c) | To invigorate blood. |
Applications:
(a)Constipation: (1) heat accumulated in constipation — Rhubarb (Da Huang, 
) is used with Glauber’s salt (Mang Xiao, 
) in the formula Da Cheng Qi Tang; (2) cold accumulation in constipation — Rhubarb (Da Huang, 
) is used with Prepared aconite root (Fu Zi, 
) and Dried ginger (Gan Jiang, 
) in the formula Wenpi Tang; (3) constipation with heat accumulation and damage to Yin — Rhubarb (Da Huang, 
) is used with Fresh Rehmannia root (Sheng Di Huang, 
), Scrophularia (Xuan Shen, 
), and Ophiopogon root (Mai Dong, 
).
(b)Extravasation due to heat in the blood, manifested as vomiting with blood and epistaxis, or upward attack by pathogenic fire, manifested as red painful swollen eyes, sore throat, and painful swollen gums. These two syndromes are treated by combining Rhubarb (Da Huang, 
), Coptis root (Huang Lian, 
), and Scutellaria root (Huang Qin, 
).
(c)Boils, carbuncles, and furuncles. Rhubarb (Da Huang, 
) is used with Peach seed (Tao Ren, 
) and Moutan bark (Mu Dan Pi, 
).
(d)Stagnation of blood, manifested as amenorrhea, postpartum retention of lochia, postpartum abdominal pain, abdominal masses, and traumatic injury. Rhubarb (Da Huang, 
) is used with Chuan Xiong, rhizome (Chuan Xiong, 
), Peach seed (Tao Ren, 
), Safflower (Hong Hua, 
), and Moutan bark (Mu Dan Pi, 
).
(e)Dosage: 3–12 g.
Cautions and Contraindications: The raw herb strongly promotes bowel function. Fried with wine, the herb is good for invigorating blood. The carbonized herb is applied during hemorrhagic disease. Overboiling of the herb weakens the function of purgation. This herb is contraindicated during menstruation and pregnancy.
Glauber’s salt (Mang Xiao, 芒硝)
Pharmaceutical Name: Natrii Sulfas
Part Used: Sodium sulfate
Properties: Salty, bitter, and cold
Channel Tropism: Stomach and large intestine
| Functions: | (a) | To purge feces downward; |
| (b) | To soften hardness; | |
| (c) | To clear heat. |
Applications:
(a)Constipation. Glauber’s salt (Mang Xiao, 
) is used with Rhubarb (Da Huang, 
) in the formula Dacheng Qi Tang.
(b)Sore throat, ulcerated mouth, red eyes, or boils. Glauber’s salt (Mang Xiao, 
) is used with Borneol (Bing Pian, 
) for external use.
(c)Dosage: 10–15 g.
Cautions and Contraindications: This herb is contraindicated during pregnancy.
Hemp seed (Hua Ma Ren, 火麻仁)
Pharmaceutical Name: Fructus Cannabis
Part Used: Ripe seeds
Properties: Sweet and neutral
Channel Tropism: Spleen and large intestine
Function: To lubricate the intestines and move feces.
Applications:
(a)Constipation due to dryness in the intestines. Hemp seed (Hua Ma Ren, 
) is used with Chinese Angelica root (Dang Gui, 
), Prepared Rehmannia root (Shu Di Huang, 
), and Apricot seed (Xing Ren, 
).
(b)Constipation with hemorrhoids due to dryness and heat in the large intestine. Hemp seed (Hua Ma Ren, 
) is used with Rhubarb (Da Huang, 
) and Magnolia bark (Hou Po, 
).
(c)Dosage: 9–30 g.
Cautions and Contraindications: This herb is contraindicated in cases with diarrhea.
Bush cherry seed (Yu Li Ren, 郁李仁)
Pharmaceutical Name: Semen pruni
Part Used: Ripe seeds
Properties: Pungent, bitter, and neutral
Channel Tropism: Small and large intestines
| Functions: | (a) | To lubricate the intestines and move feces; |
| (b) | To promote urination. |
Applications:
(a)Constipation due to dryness in the intestines. Bush cherry seed (Yu Li Ren, 
) is used with Apricot seed (Xing Ren, 
), Peach seed (Tao Ren, 
), and Arborvitae seed (Bai Zi Ren, 
).
(b)Edema. Bush cherry seed (Yu Li Ren, 
) is used with Mulberry bark (Sang Bai Pi, 
), Phaseolus seed (Chi Xiao Dou, 
), and Imperata rhizome (Mao Gen, 
).
(c)Dosage: 3–12 g.
Cautions and Contraindications: This herb is contraindicated in cases with depletion of body fluids, or during pregnancy.
Genkwa flower (Yuan Hua, 芫花)
Pharmaceutical Name: Flos Genkwa
Part Used and Dosage: Bud; 1.5–3 g
Properties: Pungent, bitter, warm, and toxic
Channel Tropism: Lung, kidney, and large intestine
| Functions: | (a) | To transform water and stop cough; |
| (b) | To resolve phlegm and stop cough; | |
| (c) | To kill worms. |
Applications:
(a)Edema of the face or body, ascites, and retention of fluid in the chest. Genkwa flower (Yuan Hua, 
) is used with Kansui root (Gan Sui, 
) and Peking spurge root (Da Ji, 
).
(b)Sudden cough and cold-damp type of chronic bronchitis. Genkwa flower (Yuan Hua, 
) is used with Jujube (Da Zao, 
).
(c)Scabs, white ringworm, and stubborn ringworm. Genkwa flower (Yuan Hua, 
) is ground into powder and combined with powdered Realgar (Xiong Huang, 
) and pig fat oil for external application.
(d)Dosage: 1.5–3 g.
Cautions and Contraindications: This herb must not be used with Licorice root (Gan Cao, 
), as they counteract each other. It is contraindicated during pregnancy.
Kansui root (Gan Sui, 甘遂)
Pharmaceutical Name: Radix kansui
Part Used: Tuberous root
Properties: Bitter, sweet, cold, and toxic
Channel Tropism: Lung, kidney, and large intestine
| Functions: | (a) | To transform water and reduce edema; |
| (b) | To disperse nodules and relieve swelling. |
Applications:
(a)Edema and a full sensation in the abdominal region. Kansui root (Gan Sui, 
) is used with Pharbitis seed (Qian Niu Zi, 
).
(b)Ascites. Kansui root (Gan Sui, 
) is used with Peking spurge root (Da Ji, 
) and Genkwa flower (Yuan Hua, 
).
(c)Retention of water or fluid in the chest. Kansui root (Gan Sui, 
) is used with Rhubarb (Da Huang, 
) and Glauber’s salt (Mang Xiao, 
).
(d)Boils, carbuncles, and furuncles. Kansui root (Gan Sui, 
) is ground into powder and mixed with water for external application.
(e)Dosage: 0.5–1 g.
Cautions and Contraindications: This herb is best used in pill and powder form. It should not be used with Licorice root (Gan Cao, 
) and is contraindicated during pregnancy.
Purgative Prescriptions
Da Cheng Qi Tang （大承气汤）
(Major Purgative Decoction)
(Major Purgative Decoction)
| Composition: | Rhubarb (Da Huang,  ) |
12 g |
Magnolia bark (Hou Po,  ) |
15 g | |
Immature bitter orange (Zhi Shi,  ) |
12 g | |
Mirabilitum (Mang Xiao,  ) |
9 g |
Administration: Decoct Hou Po 
and Zhi Shi 
before Da Huang 
Mang Xiao 
is infused into the decoction after removing the residue.
Functions: Drastic purgation for eliminating accumulated heat.
Indications: Excessive-heat syndrome of the Yangming-fu organs, manifested as constipation, abdominal pain with tenderness, afternoon fever, thirst with a great desire to drink, a reddened thorny tongue with a dry yellowish coating or a dry blackish coating with fissures, and a deep forceful pulse.
Formula Analysis: The syndromes are caused by pathogenic heat accumulating in the large intestine, leading to obstructed flow of fu-Qi. The treatment method is to eliminate heat to relax the bowels. Acting as the chief herb, Da Huang 
with bitter and cold properties eliminates heat, stagnated food and stools in the gastrointestinal tract, and relieves constipation. The salty and cold Mang Xiao 
, which moistens dryness and softens masses, is used as the assistant herb to reinforce the effect of the chief herb. The two herbs enhance mutual potency, with strong potency of drastically purging heat accumulation. Zhi Shi 
and Hou Po 
, used as adjuvant herbs, promote the flow of Qi and relieve the feeling of fullness. They help the chief and assistant herbs remove the stagnated food and stools to accelerate the discharge of heat and masses. The four herbs generate effect in purging heat and masses synergistically. The formula drastically purges heat accumulation and descends stomach Qi, as well as unblocks the accumulation and stagnation.
Applications in Bio-medicine: Appendicitis, intestinal obstruction, acute abdominal pain, and high fever.
Modifications:
(a)In cases of mild damage to body fluid, omit Mang Xiao 
and create the formula called Xiao Cheng Qi Tang.
(b)In cases of mild abdominal distension and fullness, replace Hou Po 
and Zhi Shi 
with Baked licorice (Zhi Gan Cao, 
). This formula is known as Tiaowei Cheng Qi Tang.
(c)For severe abdominal fullness and pain, add Radish seed (Lai Fu Zi, 
), Peach seed (Tao Ren, 
) and Red peony (Chi Shao, 
).
(d)For severe Qi and blood deficiency, add Ginseng (Ren Shen, 
), Chinese Angelica root (Dang Gui, 
) and Licorice (Gan Cao, 
) This formula is called Huanglong Tang.
(e)For severe intestinal dryness, manifested as constipation, replace Hou Po 
and Zhi Shi 
with Scrophularia (Xuan Shen, 
), Fresh Rehmannia root (Sheng Di Huang, 
), and Ophiopogon root (Mai Dong, 
), creating the formula called Zengye Cheng Qi Tang.
Cautions: This formula must be applied with great care to those with excess syndromes of the Yangming-fu organs that are not suffering from excess heat or who have constitutional deficiencies of Qi and yin. Great caution is also advised in treating the aged, those with general asthenia, and pregnant women with this formula.
Wenpi Tang （温脾汤）
(Spleen-Warming Decoction)
| Composition: | Rhubarb (Da Huang,  ) |
12 g |
Prepared aconite root (Fu Zi,  ) |
9 g | |
Dried ginger (Gan Jiang,  ) |
6 g | |
Licorice (Gan Cao,  ) |
3 g | |
Ginseng (Ren Shen,  ) |
9 g |
Administration: The last four herbs are cooked with water first, then decocted together with Da Huang 
.
| Functions: | (a) | To eliminate cold waste accumulation; |
| (b) | To warm and invigorate spleen-Yang. |
Indications: Cold accumulation syndrome due to Yang deficiency, marked by abdominal pain, constipation, or protracted diarrhea with pus and blood, cold limbs, a pale tongue with a thin whitish coating, and a deep taut pulse.
Formula Analysis: This is the commonly used formula for the syndrome which results from deficiency of spleen-Yang, leading to the generation of cold and further cold accumulation in the intestines. The syndrome should be treated by purging the accumulated cold, and warming and invigorating the spleen-Yang. In this formula, Fu Zi 
with extremely acrid and hot properties, which warms and strengthens the spleen-Yang, dispels cold, and relieves pain, and Da Huang 
with bitter and cold properties, which purges accuimulated masses, are used together as the chief herbs. Gan Jiang 
, the assistant herb, helps Fu Zi 
warm and strengthen the middle Jiao and dispel cold. Ren Shen 
and Gan Cao 
, the adjuvant herbs, have the functions of replenishing Qi and nourishing blood, regulating the middle Jiao, enhancing body resistance and eliminating pathogenic factors, and reinforcing the spleen in conjunction with Fu Zi 
and Gan Jiang 
. Meanwhile, Gan Cao 
also serves as the guiding herb to mediate the properties of the other herbs.
Applications in Bio-medicine: Chronic dysentery and habitual constipation, with the following chief symptoms: abdominal pain, constipation, lassitude, and aversion to cold with a preference for warmth. These conditions pertain to the syndrome of interior cold accumulation due to deficiency of Yang Qi.
Modifications:
(a)For severe abdominal distension and pain, add Costus root (Mu Xiang, 
) and Magnolia bark (Hou Po, 
).
(b)For significant tenesmus, add immature bitter orange (Zhi Shi, 
).
(c)In cases of severe nausea and vomiting, add Pinellia tuber (Ban Xia, 
) and Amomum fruit (Sha Ren, 
).
Ma Zi Ren Wan （麻子仁丸）
(Hemp Seed Pill)
| Composition: | Cannabis seed (Ma Zi Ren,  ) |
500 g |
White peony root (Bai Shao,  ) |
250 g | |
Immature bitter orange (Zhi Shi,  ) |
250 g | |
Rhubarb (Da Huang,  ) |
500 g | |
Magnolia bark (Hou Po,  ) |
250 g | |
Apricot seed (Xing Ren,  ) |
250 g |
Administration: The herbs are ground into a powder and mixed with honey to make pills. Take 9 g of the powder with warm boiled water twice per day.
| Functions: | (a) | To moisten the intestines and dispel heat; |
| (b) | To promote Qi circulation and bowel movement. |
Indications: Constipation due to dryness and heat in the stomach and intestines, marked by dry stool, frequent urination, dry mouth and tongue, and a slight yellowish tongue coating.
Formula Analysis: This is the commonly used formula for gastrointestinal dryness and heat, deficiency of body fluid, and lack of lubrication in the intestine. The syndrome should be treated by moistening the bowels to purge heat, and promoting the flow of Qi to relieve constipation. In the formula, Ma Zi Ren 
functions as the chief herb. It is mild in nature and abundant in lipids, and moistens the large intestine for relieving constipation. Supporting the chief herb are Da Huang 
, which purges heat and dryness from the stomach and intestine, Xing Ren 
, which descends lung-Qi and relaxes the bowels, and Bai Shao 
, which nourishes Yin, astringes body fluid, and mediates the interior and relieves spasm. The preceding three herbs are assistant herbs. Zhi Shi 
and Hou Po 
promote the flow of Qi and dissolution of masses, enhancing the effect of Da Huang 
, and serving as adjuvant herbs. The two herbs enhance the potency of descending Qi, purging heat and promoting bowel movement. Administration with honey further strengthens the effect of moistening dryness and relaxing the bowels.
Applications in Bio-medicine: Habitual constipation, senile constipation, postpartum constipation, and constipation following hemorrhoid surgery, which pertain to gastrointestinal dryness and heat syndrome.
Modifications: For constipation due to hemorrhoids, add Burnet root (Di Yu, 
) and Sophora flower (Huai Hua, 
).
Cautions: It is contraindicated in cases of constipation due to exhaustion of body fluids and blood, and a lack of nutrients in the large intestine without symptoms of dryness and internal heat.
Shizao Tang （十枣汤）
(Ten-Jujube Decoction)
| Composition: | Genkwa (Yuan Hua,  ) |
20 g |
Kansui root (Gan Sui,  ) |
20 g | |
Jujube (Da Zao,  ) |
10 pcs | |
Thistle (Da Ji,  ) |
20 g |
Administration: All herbs except Jujube are ground together into a powder; then ten pieces of Jujube are decocted separately. The powder is taken with the decoction early in the morning before eating, 0.5–1 g per day.
Function: To Eliminate fluid retention.
Indications: Fluid retention in the hypochondrium, and edema, marked by a cough which causes pain in the chest and hypochondrium, shortness of breath, headache, dizziness, a deep taut pulse; or severe edema of the body, abdominal fullness, dyspnea, and difficulty in urination and defecation.
Formula Analysis: The syndrome is caused by excessive fluid retention in the interior, which is treated by purgation. In this formula, Gan Sui 
promotes the circulation of fluid and dampness of meridians and collaterals, while Da Ji 
purges pathogenic fluid from the Zang–Fu organs, intestine, and stomach, and Yuan Hua 
eliminates the retained fluid and accumulated phlegm of the chest and hypochondrium. The three herbs have their respective advantages and, when combined, enhance the effect of eliminating retained fluid and relieving edema and fullness. However, they are toxic in nature, with a drastic effect, and are apt to impair body resistance. Thus, the inclusion of Da Zao 
in the decoction is meant to reinforce the spleen and stomach, protect the stomach to reduce the reactions after drinking, reduce toxicity, and moderate the drastic effects. It functions as adjuvant herb.
Applications in Bio-medicine: Exudative pleurisy, ascites due to cirrhosis, and chronic nephritic edema, which pertain to excessive fluid retention while there is still strong body resistance.
Cautions:
(a)The above composition except for Jujube should not be decocted, otherwise they will lose their effectiveness.
(b)This formula is contraindicated during pregnancy.
(c)It is also contraindicated in persons with weak constitutions.