What it is:
This herb is the prepared root of Rehmannia glutinosa Libosch. (family Scrophulariaceae) , which is mainly produced in Henan, Hebeiand Inner Mongolia. The root is dug in autumn, dried after getting rid of the rootlets. The dried root is mixed with yellow rice or milletwine, amomum fruit and tangerine peel, and then steamed anddried in the sun alternately and repeatedly until it turns black inside as well as outside with a soft, sticky and greasy texture, and then sliced for use.

Property:
Sweet in flavour, slightly warm in property, acting on the liver and kidneychannels.

Effects:
Nouri-shing the blood,tonifying yin, and replenishing the vital essence and marrow.

Used for:
1. Blood deficiency syndrome manifested as sallow complexion, dizziness, blurred vision, palpitation, insomnia,irregular menstruation, metrorrhagia and metrostaxis. It is often used to-gether with chinese angelica root, whitepeony root andchuanxiong rhizome, as in Decoction of Four Ingredients(Siwu Tang).

2. Tidal fever, night sweat, seminalemission, and diabetesdue to deficiency ofthe kidney-yin. It is often used with chinese yam and dogwood fruit, as inBolus of Six herbs Including Rehmannia (Liuwei Dihuang Wan).

3. Dizziness, blurred vision,tinni-tus, deafness and premature grey hair due to deficiency ofthe vital essence and blood. It is often used with fleece-flower root, glossy privet fruit,eclipta,dogwood fruit,etc.

Dosage and admi-nistration: 10-30g, decocted in water for oral adminis-tration.

Precautions:
This herb is sticky and greasy in pro-perty and can hinderdigestion, so it should not be pre-scribed for patientsafflicted with stag-nation of qi, profusephlegm, gastric and abdominal distension,poor appetite and loose stool.