Furanocoumarins, such as bergapten and psoralen, which are in dong quai have been widely studied for their phototoxicity; however, only Angelica gigas (Korean angelica) has been demonstrated to cause photodermatitis.
Safrole, found in the volatile oil, is a potential carcinogen; however, no specific cases of carcinogenesis have been reported.
High doses of dong quai volatile oil have been reported to cause nephrosis in rats but there are no reports in humans.
Case reports suggest the elevations in prothrombin and INR may occur when dong quai is used with warfarin — use caution if used concurrently with warfarin.
Contraindications and Precautions
Because dong quai may have oestrogenic effects, women with hormone-sensitive tumours, endometriosis and uterine fibroids should avoid using dong quai.
Dong quai may stimulate uterine contractions and is therefore contraindicated in pregnancy.
Practice Points / Patient Counselling
• Dong quai is a popular Chinese medicine used widely to relieve menopausal symptoms; however, controlled trials in humans are lacking. In practice, dong quai is prescribed together with other herbs and may be effectivewhen used in this way.
• Evidence of oestrogenic activity is contradictory.
• Care is required in people using drugs that affect blood clotting.
• Dong quai is generally safe when used appropriately.
Answers to Patients’ Frequently Asked Questions
What will this herb do for me?
Dong quai has a long history of use as a women’s tonic. Although conclusive evidence is lacking, dong quai is used in conjunction with other herbs to assist in menopausal and menstrual complaints, and may be effectivewhen used in this way.
When will it start to work?
It is difficult to predict from the available scientific research.
Are there any safety issues?
Dong quai appears to be relatively safe but care should be taken in people using drugs that affect blood clotting or in pregnancy and conditions that are hormone sensitive.