Dong Quai (Angelica sinensis): What the Research Says

There are medicinal herbs whose reputation is built over thousands of years, long before modern science even knew how to test them, and Dong Quai is a prime example of this. In traditional Chinese medicine, it is considered one of the main herbs for women's health, so much so that it earned the nickname "female ginseng." Women take it for irregular menstruation, menstrual cramps, menopausal symptoms, and general strengthening. It has sat on the shelves of health food stores and Eastern pharmacies for decades, wrapped in an aura of ancient wisdom and a natural solution to problems that trouble millions of women.

But here is precisely where it is important to stop and ask the question we always ask: What does the human research actually show? And the answer, in the case of Dong Quai, is disappointing. The most well-known controlled clinical trial, from 1997, found no advantage of Dong Quai alone over a placebo in relieving menopausal hot flashes. At the same time, it turns out the herb is not as innocent as one might think: it has a real blood-thinning effect and causes increased sensitivity to the sun. In this article, we will explain what Dong Quai is, what traditional medicine stands behind it, what science actually says, and why we rated it yellow: traditional and popular, but with weak evidence and cautionary points that cannot be ignored.

What is Dong Quai?

Dong Quai is the Chinese name for the root of the plant Angelica sinensis, a species of angelica that grows in China, Japan, and Korea. Here is what is important to understand about it:

• It is a dried root from Chinese medicine. The commonly used part is the root, which is dried and ground into powder, boiled in soup, or extracted into a tincture. In Chinese, its name is "Dang Gui" (當歸).
• It is considered a leading herb for women's health. In Chinese medicine, it is classified as a "blood-nourishing" and "blood-moving" herb, used for irregular menstruation, menstrual cramps (dysmenorrhea), menopausal symptoms, and general weakness.
• It contains coumarins and ferulic acid. Among the active ingredients identified in it are polysaccharides, phthalides (such as ligustilide), ferulic acid, and compounds from the coumarin group, some of which affect blood clotting.
• It is sold as a supplement in capsules, powder, and tinctures. In the West, it is common as capsules of root extract, while in the East it is often part of a herbal formula or soup.

A central point that recurs throughout the story: In traditional Chinese medicine, Dong Quai is almost never given alone. It is an ingredient in complex herbal mixtures, where it is coordinated with other herbs according to an individual diagnosis. This is a critical fact, since almost all Western research tests the herb alone, precisely the way it is almost never consumed in the tradition from which it comes.

The Connection to Women's Health: The Theoretical Mechanism

The idea behind Dong Quai as an herb for women's health was based on the assumption that it has estrogen-like activity (phytoestrogenic), meaning that certain compounds in it mimic the action of the hormone estrogen in the body. If this were true, it could explain why it might help with menopausal symptoms, many of which result from a decline in estrogen levels.

Another mechanism attributed to it is "moving blood" and improving blood flow in the pelvis, an idea that aligns with the Chinese medicine perspective and the presence of ferulic acid and coumarins that affect blood vessels and clotting. According to this view, improved flow should relieve menstrual cramps and irregularity.

But here precisely lies the critical difference between theory and reality. A plausible mechanism is not a substitute for clinical proof, and when the estrogen hypothesis was directly tested, it was not confirmed. Moreover, if the herb truly has an effect on clotting, this is a double-edged sword: it could explain a potential benefit, but also pose a real safety risk. Precisely because of the gap between theoretical logic and data, it is important to move on to what human studies actually found.

Current Evidence

Study 1: The Controlled Trial by Hirata and Colleagues from 1997

This is the most important and most cited clinical trial on the subject, and also the most disappointing for herb enthusiasts. In 1997, Hirata and colleagues, from the Kaiser Permanente group in California, published a double-blind, placebo-controlled trial in the prestigious journal Fertility and Sterility, which tested whether Dong Quai has an estrogenic effect and whether it relieves menopausal symptoms.

The study included 71 postmenopausal women (average age about 52), randomly divided into a Dong Quai group or a placebo group for 24 weeks. The researchers examined objective measures: endometrial thickness via ultrasound, vaginal cell maturation (a marker of estrogenic activity), as well as the Kupperman index and a hot flash diary. The conclusion was unequivocal: Dong Quai, when given alone, does not elicit an estrogen-like response and is no more effective than a placebo in relieving hot flashes and menopausal symptoms. This is one of the few high-quality trials on the subject, and its negative result left a deep mark on the scientific evaluation of the herb.

Study 2: The Limitation of "Herb Alone" vs. Traditional Mixtures

Here enters the complexity that accompanies almost every study on Dong Quai. In Chinese medicine, it is almost always part of a mixture, and it is sometimes argued that negative results from the herb alone do not reflect the traditional method of use. Indeed, some studies on herbal mixtures containing Dong Quai have sometimes shown mixed results, but they are also often small, of moderate methodological quality, and it is difficult to attribute the effect specifically to Dong Quai rather than the other components.

The problem is twofold: On one hand, testing the herb alone (as in Hirata's study) shows a lack of clear benefit. On the other hand, testing mixtures does not allow isolating the contribution of Dong Quai itself. The result is that to this day, there are no strong and consistent human evidence supporting Dong Quai as an effective and independent treatment for any of its common uses, whether for menstruation, menstrual cramps, or menopause.

Study 3: Hot Flashes in Men, Another Negative Piece of Evidence

To examine the herb in another context, a randomized, double-blind, placebo-controlled trial was also conducted in men suffering from hot flashes following androgen deprivation therapy (hormonal treatment for prostate cancer). Here too, a controlled and independent test of the herb did not yield a convincing result, and Dong Quai was not found to significantly reduce hot flashes compared to a placebo.

The pattern that repeats itself is clear: The more controlled, randomized, and double-blind the trial, and the more it examines Dong Quai alone, the claimed benefit tends to disappear. This is precisely the hallmark of an effect based more on tradition, expectation, and placebo than on a measurable pharmacological effect.

What About Safety, Blood Thinning, and Sun Sensitivity?

This is perhaps the most important part of this article, since Dong Quai is not an "innocent" herb that can be taken without thought. First and foremost, Dong Quai has a real blood-thinning and clotting-slowing effect. The herb contains coumarins and ferulic acid with antiplatelet and anticoagulant activity. A classic case report was documented where a woman taking warfarin (a blood-thinning medication) added Dong Quai, and her INR value (a clotting measure) dangerously rose to about 4.9, returning to normal only after stopping the herb. This is not a theoretical warning: combining Dong Quai with warfarin, aspirin, or any other blood thinner may increase the risk of bleeding. Anyone taking anticoagulant medications, or about to undergo surgery or a medical procedure, must avoid it or consult a doctor.

Second, Dong Quai causes increased sensitivity to the sun (photosensitivity). The herb contains furanocoumarins (such as psoralen and bergapten), photoreactive compounds known for their ability to provoke skin reactions upon exposure to sunlight, including rash, irritation, and increased susceptibility to sunburn. Some of these furanocoumarins are even considered to have photocarcinogenic potential. Anyone taking the herb should protect their skin from the sun.

Third, Dong Quai should be avoided during pregnancy and breastfeeding, as it is considered a stimulant of uterine muscles and there is concern about its effect on pregnancy, and there are insufficient safety data. Also, due to the suspicion of hormonal activity, caution should be exercised in hormone-sensitive conditions such as breast cancer, uterine or ovarian cancer, and a doctor should be consulted before taking it.

Should You Take Dong Quai?

This is one of the supplements we rated Yellow: an herb with a rich tradition and genuine popularity, but weak human evidence that does not support the promises, along with safety points that require attention. Here are the considerations honestly:

• The evidence for menopause is negative. Hirata's controlled trial found no advantage over placebo for hot flashes and no estrogenic activity. If the goal is menopausal symptoms, there are approaches with a much stronger evidence base.
• The evidence for menstruation and menstrual cramps is weak. There are no strong, independent human evidence for Dong Quai alone for these uses. Most support comes from tradition or mixtures from which the herb's contribution cannot be isolated.
• It thins blood, and this is a real warning. It must not be combined with warfarin, aspirin, or other blood thinners, and should be stopped before surgery.
• It causes sun sensitivity. Use requires sun protection due to its furanocoumarins.
• It is forbidden during pregnancy and breastfeeding, and caution is needed in hormone-sensitive conditions. These are not merely theoretical warnings.

It is important to clarify: Dong Quai is not a "bad medicine," and it has been studied and consumed for generations. But the lack of strong independent evidence on one hand, and a safety profile requiring caution on the other, clearly place it in the yellow category. It is not a magic solution, and certainly not a supplement that can be taken without considering other medications you are taking.

What to Take Away from the Research?

1. Do not expect a miracle from Dong Quai alone. The highest quality controlled trial found no advantage over placebo for hot flashes. If it helps you personally, great, but know that part of the relief may be a placebo effect.
2. If you take blood thinners, do not touch it without a doctor. Dong Quai plus warfarin is a documented and dangerous combination (INR rose to 4.9). This is the most important point in the article.
3. If you suffer from significant menstrual cramps or menopausal symptoms, talk to a doctor. There are approaches with a stronger evidence base, and sometimes severe symptoms require medical investigation.
4. Protect your skin from the sun if you take the herb. Its furanocoumarins increase sensitivity to sun and burns.
5. If you are pregnant, breastfeeding, or have a hormone-sensitive condition, avoid it and consult a doctor. In these cases, caution is especially important.

For those who still want to try it anyway, you can purchase Dong Quai (Angelica sinensis) on iHerb in various forms. To check which supplements are truly suitable for your health goals, including hormonal balance and women's health, and according to the quality of evidence for each, it is recommended to use our personal supplement checker that rates each supplement honestly according to science.

The Broader Perspective

Dong Quai is an excellent case study for the principle we consistently hold: Traditional longevity is not scientific evidence. An herb can be studied and consumed for thousands of years, be valued as "female ginseng" and sit in every health cabinet, and still not pass the test of a controlled trial when examined rigorously. This story repeats itself again and again in the world of supplements and herbs: an impressive tradition, a tempting theoretical mechanism, and then, when research becomes rigorous and controlled, the benefit diminishes or disappears.

The practical lesson is twofold. First, when it comes to a real problem that troubles you, menstrual cramps or menopausal symptoms, you deserve a treatment that actually works, not an herb with weak evidence. It is worth directing your energy (and money) toward evidence-based directions. Second, Dong Quai reminds us that "natural" is not synonymous with "safe". An herb that thins blood, causes sun sensitivity, and is forbidden during pregnancy is not child's play, and its traditional aura does not negate the risks. And this is precisely the honest perspective we commit to: rating each supplement according to what science shows, on benefit and risk, even when the answer is not what everyone wants to hear.

References:
Hirata JD. et al., Does dong quai have estrogenic effects in postmenopausal women? A double-blind, placebo-controlled trial, Fertility and Sterility, 1997 Dec;68(6):981-986 (PMID: 9418683, DOI: 10.1016/S0015-0282(97)00397-X)
Ge B. et al., Interaction between warfarin and Chinese herbal medicines, 2014 (PMC4325561)