Dong quai may interact with the following medications and herbs:

Warfarin
Dong quai can increase the potency and, therefore, potential risks of blood-thinning medications, such as warfarin, so it should not be taken with these medicines.

Hormone medications
Although there is little research on the use of dong quai with hormone medications such as estrogens, progesterones, oral contraceptives, tamoxifen or raloxifene, health practitioners advise against using them together due to the possibility of adverse effects.

Blood-thinning herbs
Although reported extremely rarely and not published in the scientific literature, combining dong quai with other herbs that thin the blood could possibly increase the risk of bleeding in some people. Herbs with such potential that should be used only with tremendous caution and supervision when combined with dong quai include feverfew (Tanecetum parthenium), garlic (Allium sativum), ginger (Zingiber officinale), ginkgo (Ginkgo biloba), ginseng (Asian ginseng), licorice (Glycyrrhiza glabra), chinese skullcap (Scutellaria baicalensis), and turmeric (Curcuma longa).

Herbs or medications that cause sun sensitivity
Given that dong quai may increase an individual's sensitivity to sunlight, it should not be taken with other medications or herbs (such as St. John's wort) that cause the same reactions.