Angelica sinensis is the plant commonly referred to as dong quai, tang kuei and tang kwei. It is a member of the Umbelliferae, or carrot family.  Botanically, dong quai is a perennial plant growing to about 0.5 - 1 meter in height.  The inferior leaves are tripinnate and the superior leaves are pinnate on long, sheathed petioles. The flowers are white and the root is grey-dark brown in color, having a wrinkled appearance. The root is the part of the plant that is used medicinally. Preparations taste bitter, are aromatic and slightly sweet. 
Dong quai has a long history of use in Traditional Chinese Medicine. It is native to China, Korea, and Japan, and has been used medicinally by these cultures for thousands of years. The traditional view of dong quai is that it provides an effective means to strengthen the heart, lungs, and liver meridians, and to lubricate the bowel.  It is often referred to as a blood mover. Dong quai is also recognized as the chief female tonic, of equivalent importance as ginseng is to males.
The main constituents in dong quai include volatile oils, accounting for 0.4 - 0.7 % of the plant (includes ligustilide and n-butylidenephthalide), phytosterols, ferulic acid, coumarins (angelol and angelicone), and flavonoids. [4-6] Dong quai also contains vitamin A, vitamin C, vitamin B12, vitamin E, nicotinic acid, folic acid and folinic acid, calcium, and magnesium. 
Ferulic acids have been shown to act as pain relievers and fever reducers. They may also inhibit platelet aggregation and serotonin release.  Certain coumarins, namely dihydropyranocoumari dihydrofruanocoumarins, obtained from Umbelliferous plants have been shown to possess significant coronary vasodilatory, spasmolytic, and c-AMP phosphodiesterase inhibiting activity via calcium channel antagonism. 
Dong quai has also demonstrated activity with cardiopulmonary receptors and has been shown to depress stimulation of b-2-adrenergic receptors.  This is of particular importance in reducing experimental pulmonary hypertension. In addition, Dong quai can prolong the refractory period, correct experimental atrial fibrillation, and is a negative inotropic in the heart.
Medicinal actions ascribed to dong quai include;
- uterine stimulant
- emmenagogue (stimulate menstruation)
- estrogenic and progesterogenic
- fetal relaxant
- nervous sedative
- mild laxative
- cardiovascular relaxant
- enriches the blood
- anti-platelet aggregant
- demulcent laxative
- white blood cell stimulant
In terms of Traditional Chinese Medicine, dong quai tonifies the blood, regulates menses, invigorates and harmonizes the blood, moistens the intestines, and treats dry stool from xue xu (or blood deficiency). 
Dong quai is widely regarded for its use in treating disorders of the female reproductive system. In experimental studies, the volatile oil portion of dong quai has demonstrated the ability to both relax and increase uterine contractions. [7, 11] Some authorities have suggested that Dong quai possesses estrogenic activity, however the evidence from an important clinical trial does not support such a finding.  Thus, its activity in the reproductive system must be attributed to other medicinal activities.
Clinical trial evidence has supported the use of Dong quai for dysmenorrhea (painful menstruation). A constituent of Dong quai, ligustilide, was administered to women with dysmenorrhea at a dosage level of 450 milligrams daily.  The results showed that the constituent alone had significantly more effectiveness in reducing symptoms than the aqueous extract of the whole plant.
Another trial supported the use of Dong quai for the treatment of infertility in women. Women with infertility due to tubal occlusion received uterine irrigation with an extract of Dong quai for 9 months.  The results showed that 79% regained patency of the fallopian tube, and a significant number of patients (53%) became pregnant.
Dong quai has been recommended by many as a treatment for menopause. However, the results of one large trial does not support this use and evidence for dong quai’s benefit in relieving menopausal symptoms has yet to be published. 
Dong quai has been studied for the treatment of conditions other than female reproductive disorders. Subjects with either chronic hepatitis (inflammatory liver disease) or cirrhosis of the liver were administered an extract of dong quai.  The results demonstrated that in 60% of the patients, abnormal protein metabolism and abnormal thymol turbidity tests were improved. Plasma protein levels were also increased after a treatment period of 1-3 weeks.
Dong quai may be beneficial for patients with Beurger’s disease, which is a particular type of peripheral vascular disease.  It may also help constrictive aortitis, angina, stroke, and other forms of peripheral vascular disease. Practitioners also use dong quai to treat premenstrual syndrome, chronic pelvic infections, constipation anemia, sciatica, thrombosis and arthritis.  Analgesic properties have also been demonstrated by, and attributed to, this medicinal plant.
Dosages are dependent on the type of preparation and the intended condition to be treated. For dysmenorrhea, a dropper full of tincture taken every 1 - 3 hours at the first sign of pain is often sufficient.  Generally, if taking a decoction of the root: one heaping teaspoon (or 3 - 4 grams) per cup of water, taken 1-4 times daily; 4 - 8 milliters of a 1:2 liquid extract daily, are the recommended doses. [1, 2] Dong quai preparations can usually be taken long term, as its effect is often tonic in nature.
Caution is advised with Dong quai use during diarrhea due to its mild laxative action. Considering its emmenogogue and uterine stimulating effect, caution should be observed during pregnancy with complete avoidance in the early trimesters. It is also contraindicated in hemorrhagic conditions and acute viral infections. 
Traditional Chinese Medicine practitioners have advised against its use in damp obstruction in the lower jiao (area from navel to hipbone, or Pelvic region). Dong quai should also not be used in yin (fluid, most commonly blood) deficiency with heat signs. 
Dong quai may interact with anti-coagulant medications. In animal studies, dong quai administered to animals given warfarin significantly lowered prothrombin time within 3 days of co-administration.  A case study in a patient taking warfarin who had started dong quai therapy also revealed changes in blood clotting parameters.  Therefore, patients on anticoagulants should take caution if considering dong quai treatment and must discuss its use with their physician.
Adverse effects of dong quai use include photosensitivity, which is likely due to furanocoumarins in the plant.  A case report of gynecomastia was recorded in a patient who took dong quai capsules for 1 month; however, this condition regressed upon discontinuation of the supplement.  Contamination of the product was not assessed. Additionally, no overdose symptoms have been reported with the use of dong quai-containing supplements.
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