Dong quai is often recommended as a treatment for menstrual cramps, premenstrual syndrome (PMS), and other problems related to menstruation, as well as hot flashes and other menopausal symptoms. However, the scientific evidence supporting these uses is very weak, consisting primarily of test tube and animal studies, as well as a few open studies of people.^1-5 Only double-blind, placebo-controlled studies can actually show a treatment effective, and a 24-week study that compared the effects of dong quai against a placebo in 71 postmenopausal women found no benefit.⁶ (For more information on why double-blind studies are so important, see Why Does This Database Rely on Double-blind Studies?)

We recommend using dong quai under the supervision of an herbalist qualified in traditional Chinese herbal medicine, not because the herb is dangerous, but because it is difficult to self-prescribe Chinese herbal formulas.

If you wish to self-treat with dong quai, a typical dosage is 10 to 40 drops of dong quai tincture 1 to 3 times daily, or 1 standard size 00 gelatin capsule, 3 times daily.

Dong quai is generally believed to be nontoxic. According to Chinese studies, which may not have been up to current scientific standards, very large amounts have been given to rats without causing harm.⁷ Side effects are rare and primarily consist of mild gastrointestinal distress and occasional allergic reactions (such as rash).

Contrary to popular belief, dong quai does not appear to have estrogen-like actions.^8,9 However, according to an article in the Singapore Medical Journal, a 35-year-old man who used a prepared herbal formula called Dong Quai pills developed enlargement of his breasts.¹⁰ Such enlargement would typically result if a man used estrogen. The authors of the article blamed the dong quai itself. However, a more likely explanation is that the prepared herbal formula was "spiked" with synthetic estrogen. There are numerous reports of prepackaged Asian herb products containing unlabeled constituents, including conventional medications designed to enhance their effect.^11,12

Interestingly, in a test-tube study, dong quai was again found to be nonestrogenic, and yet it nonetheless stimulated the growth of breast cancer cells.¹⁵ Although the mechanism of this effect is not known, the results suggest that women who have had breast cancer should avoid using dong quai.

Dong quai may interact with the blood-thinning drug warfarin (Coumadin), increasing the risk of bleeding, according to one case report.¹³ Dong quai might also conceivably interact with other blood-thinning drugs, such as heparin, aspirin, clopidogrel (Plavix), ticlopidine (Ticlid), or pentoxifylline (Trental).

Certain constituents of dong quai can cause photosensitivity (increased sensitivity to the sun), but this has not been observed to occur in people using the whole herb.

Safety in young children, pregnant or nursing women, or those with severe liver or kidney disease has not been established. One case report suggests that dong quai usage by a nursing mother caused elevated blood pressure in both the mother and child.¹⁴

If you are taking blood-thinning drugs, such as warfarin (Coumadin) , heparin, clopidogrel (Plavix), ticlopidine (Ticlid), pentoxifylline (Trental), or aspirin, dong quai might interact and increase the risk of bleeding.