Some studies show that combination products which include dong quai may be useful in the treatment of erectile dysfunction as well as menstrual cramps and PMS (premenstrual syndrome). It is not clear if dong quai would be useful on its own in the treatment of any of the conditions listed above. Further research is required to fully determine dong quai's effectiveness on these conditions.
To date, research results on dong quai are not conclusive enough to prove any of the health claims associated with the herb. Only a handful of clinical trials on dong quai have been conducted. Most studies have been small or have had flaws in design and reporting.
Dong quai should not be used by children or women who are pregnant or breast-feeding.
If you are experiencing increased menstrual bleeding time, or any changes in menstrual cycle, stop using dong quai and consult a health care provider.
Dong quai is usually well tolerated. There have been some reports of diarrhea and upset stomach. Stop using dong quai if you experience pain, discomfort, or tenderness in your breasts. Dong quai can cause allergic reactions and should be avoided by people with a history of allergic reactions to anise, caraway, carrot, celery, dill, or parsley. It should also be avoided if you have diarrhea, a bleeding disorder, or heavy periods.
There is an increased risk of bruising and bleeding when dong quai is taken with certain medications and other natural health products or by people with bleeding disorders. This interaction may occur between dong quai and any of the following:
- anticoagulants (e.g., warfarin, heparin)
- antiplatelets (e.g., acetylsalicylic acid [ASA], clopidogrel)
- nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., ibuprofen, indomethacin)
- panax ginseng
- sun-sensitizing medications (tretinoin, some antidepressants, cancer medication, antipsychotics, antibiotics)
- digoxin, beta-blockers (e.g., metoprolol), calcium channel blockers
Because dong quai can increase the risk of bleeding, if you are scheduled for surgery you should ask your doctor when to stop taking dong quai to reduce the risk of bleeding.
Dong quai can increase your sensitivity to light or the sun. Avoid excessive sun exposure and follow sun safety practices. Ask your pharmacist whether other medications or herbal products you are taking can further increase your sensitivity to light or sun, such as St. John's wort, some antidepressants, and antipsychotics.
Because dong quai may have properties similar to that of the female hormone estrogen, it should not be used by people with estrogen-related conditions such as cancer of the breast, uterus, or ovaries; endometriosis; or uterine fibroids. In addition, consult a health care practitioner before starting dong quai if you are taking birth control pills or if you are on hormone replacement therapy.
The safety of dong quai in large doses or for long periods of time is not clear. Discuss the benefits and risks of long-term use with your doctor.
Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health products you may be taking.