The short answer
Dong quai has been associated with excessive anticoagulation in a person taking warfarin. The signal is clinically important but rests on a case report, so the size of the risk is unknown. The available human evidence does not establish that dong quai increases warfarin absorption or its measured blood concentration.
What this answer covers
Oral Angelica sinensis preparations with oral warfarin. Other Angelica species, mixed formulas and standardized extracts with different constituents are not assumed to have identical effects.
- Supplement or preparation
- Dong quai
- Medication ingredient
- warfarin
What does the evidence show?
The original report describes a woman with stable warfarin treatment whose PT and INR more than doubled after four weeks of dong quai use. Values returned toward the acceptable range after the herb was stopped. The timing and withdrawal response support a possible interaction. A single case cannot exclude every alternative explanation, estimate how often the problem occurs or show which dong quai constituent was responsible. The report explicitly states that the mechanism was unknown.
Which forms and conditions matter?
The human report raises concern about the particular dong quai product used. A higher INR reflects a stronger anticoagulant response; it does not by itself show a higher warfarin blood level or increased absorption. Confirm the botanical species, preparation and other ingredients on the product label.
What should I discuss with my care team?
Ask the clinician managing warfarin before adding dong quai. If it is already being taken, provide the exact product, dose and start date so the clinician can assess INR follow-up and changes safely. Do not change the warfarin dose independently. No clinical timing study establishes that separating the two products by a few hours prevents this interaction.
How certain is the answer?
Case-report evidence supports a precaution but does not provide a percentage bleeding risk or a universally safe dong quai dose. The finding concerns possible excessive anticoagulation, not proof that every preparation raises warfarin concentrations. Other medicines, illness and changes in diet remain relevant when an INR changes.
Evidence and practical considerations
Side effects & toxicity
Dong quai has been associated with excessive anticoagulation in a person taking warfarin. The signal is clinically important but rests on a case report, so the size of the risk is unknown. The available human evidence does not establish that dong quai increases warfarin absorption or its measured blood concentration.
- Exact scope
- Oral Angelica sinensis preparations with oral warfarin. Other Angelica species, mixed formulas and standardized extracts with different constituents are not assumed to have identical effects. with Oral warfarin, including warfarin sodium tablets with the warfarin active moiety.
- Medication form and route
- oral warfarin
- Timing or duration
- Study-specific durations are described in each source exposure; no universally safe exposure duration has been established.
What remains uncertain
- Case-report evidence supports a precaution but does not provide a percentage bleeding risk or a universally safe dong quai dose. The finding concerns possible excessive anticoagulation, not proof that every preparation raises warfarin concentrations. Other medicines, illness and changes in diet remain relevant when an INR changes.
Factors that may matter: Exact supplement preparation and other ingredients; Starting, stopping or changing supplement intake; Baseline anticoagulation control and clinician-supervised monitoring.
Read the supporting source summaries
Source 1: current U.S. regulatory prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed oral warfarin sodium tablets.
The label advises closer INR monitoring when botanicals are started or stopped, identifies variable botanical composition and lists selected potential interactions. Vitamin K intake should remain consistent.
How this applies: Oral warfarin sodium has warfarin as its active moiety. Label-level botanical and vitamin K monitoring advice applies; it is not proof of this exact supplement effect. Oral Angelica sinensis preparations with oral warfarin. Other Angelica species, mixed formulas and standardized extracts with different constituents are not assumed to have identical effects.
Regulatory precautions do not quantify the incidence for every exact preparation or prove an interaction for an unlisted ingredient. Warfarin sodium is bridged to the warfarin active moiety only for the oral product.
Source 2: peer-reviewed original research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: One 46-year-old woman with atrial fibrillation stabilized on warfarin.
PT and INR more than doubled and returned toward the acceptable range a month after dong quai was withdrawn.
How this applies: Direct Angelica sinensis plus warfarin case. INR change is not evidence that absorption or blood concentrations increased. Exact package scope: Oral Angelica sinensis preparations with oral warfarin. Other Angelica species, mixed formulas and standardized extracts with different constituents are not assumed to have identical effects.
Single uncontrolled case; mechanism unknown and no warfarin blood concentration or absorption measurement.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Original evidence and contradictory findings assessed for this exact pair. Article drafted and existing statements adjudicated. Clinical sign-off has not been recorded. | |
| Consumer explanations clarified without changing the evidence assessment. | |
| Research summary published |
Article revision: 4285a6c960f34ddc
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.