The source is from the root and rhizome of Rheum palmatum L., R. tanguticum Maxim. ex Balf. or R. officinale Baill., family Polygonaceae. Rheum palmatum L., and R. tanguticum Maxim. ex Ball. are also called north Radix et Rhizoma Rhei, which is mainly produced at the provinces of Qinghai, Gansu, etc.; R. officinale Baill is called South Radix et Rhizoma Rhei, which is mainly produced in Sichuan Province. They are collected before the plants wither away at the end of autumn or sprout at the next spring .The hair and coat being removed, cut into pieces or lumps and then dried in the sun. The crude, or the one steamed or stir-baked with wine, or the one charred can be used for medication.

  

Bitter in flavor, cold in nature and attributive to the spleen, stomach, large intestine, liver and heart meridians.

Remove stagnation by purgation, clear away heat and purge fire, cool the blood and stop bleeding, remove toxin and promote blood circulation to remove blood stasis.

1. It is used for stagnation in the passway of the intestine and obstruction of the bowels, an essential medicihal herb to treat the syndrome of stagnation with constipation and especially effective in treatment of constipation due to stagnation of heat. For constipation due to stagnation of sthenic-heat and abdominal pain against pressing, it is usually used together with Mangxiao (Natrii Sulfas), Zhishi (Fructus Aurantii Immaturus ) and Houpo (Cortex Magnoliae Officinalis ), such as Da Chengqi Tang (Decoction); if the constipation is accompanied with deficiency of qi and blood, Renshen (Radix Ginseng), Danggui (Radix Angelicae Sinensis), etc. are added to the above prescription again to support healthy qi and attack pathogenic factors, such as Huanglong Tang (Decoction); for yin deficiency due to stagnation of heat,Shengdihuang (Radix Rehmanniae) and Maimendong (Radix Ophiopogonis), etc. are combined with, such as Zengye Chengqi Tang (Decoction); for constipation due to insufficiency of spleen yang and stagnation of cold, Fuzi (Radix Aconiti Lateralis Praeparata ) , Ganjiang (Rhizoma Zingiberis), etc. can be also combined with, such as Wenpi Tang (Decoction).

2. It is used for dysentery due to stagnation. For early stage of dysentery of dampness-heat type with abdominal pain and tenesmus, it is usually combined with Huanglian (Rhizoma Coptidis), Muxiang (Radix Aucklandiae), etc., such as Shaoyao Tang (Decoction); for abdominal pain due to food retention and unsmooth dysentery, combined with Qingpi (Pericarpium Citri Reticulatae Viride), Muxiang (Radix Aucklandiae), etc..

3. For headache, redness of eye, sore throat and swollen painful gums, and oral ulcer, etc. caused by flaring of fire, it can be used whether there is constipation or not. And it is usually combined with Huanglian (Rhizoma Coptidis), Huangqin (Radix Scutellariae), and Niuhuang (Calculus Bovis), etc. such as Xiexin Tang (Decoction).

4. It is used for bleeding due to blood-heat manifested as haematemesis and epistaxis or bleeding due to blood stasis causing blood not to attribute to channels, since it can promote blood circulation as well as purge fire and stop bleeding without blood stasis. It can be used alone or together with other medicinal herbs for cooling blood and stopping bleeding.

 

5. Oral or external use is for varicose veins, swelling and ulcer on the body surface due to toxic heat, burn and scald. For carbuncle due to toxic heat, it is usually combined with Jinyinhua (Flos Lonicerae), Pugongying (Herba Taraxaci) and Lianqiao (Fructus Forsythiae), etc.; for intestinal abscess, usually combined with Mudanpi (Cortex Moutan Radieis), Taoren (Semen Persicae), etc., such as Dahuang Mudanpi Tang (Decoction); for burn and scald, can be used alone in powder form, or combined with Diyu (Radix Sanguisorbae) powder, being mixed with sesame oil for external application.

 

It is used for postpartum abdominal pain due to blood stasis, abdominal mass, trauma and syndrome of blood retention. For postpartum abdominal pain due to blood stasis, it can be used together with Taoren (Semen Persicae), etc., such as Xiayuxue Tang (Decoction), for trauma and blood stasis with swelling and pain, used together with Taoren (Semen Persicae), Honghua (Flos Carthami), etc., such as Fuyuan Huoxue Tang (Decoction).

 

In addition, it can also clear away dampness-heat, so it is indicated for jaundice of dampness-heat type and stranguria. For jaundice, it is usually combined with Yinchen (Herba Artemisiae Scopariae), Zhizi ( Fructus Gardeniae ) , and Huangqin (Radix Scutellariae ) , etc., such as Yinchenhao Tang (Decoction) ; for stranguria due to dampness-heat in the lower energizer, it is usually combined with Mutong ( Caulis Akebiae), Cheqianzi ( Semen Plantaginis ), and Zhizi ( Fructus Gardeniae ), etc., such as Bazheng San (Powder).

 

Usage and Dosage:
5 -30 g is used in decoction for oral use, just right amount for external use, and the crude one with stronger purgative action is used for downward discharging. It is later added to decoction or soaked in boiling water for oral use, and is not decocted for a long time. That prepared with wine is suitable for blood stasis because of its better action of circulating blood. The carbonized form is usually used for bleeding syndrome.

Notes:
Used carefully or contraindicated during pregnancy, menstruation or in a case with deficiency of the spleen and stomach, and used with caution during lactation since Dahuang (Radix et Rhizoma Rhei) may induce a infant to have diarrhea.