Warfarin with Ginseng Interaction Details
Brand Names Associated with Warfarin
- Coumadin®
- Jantoven®
- Warfarin
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 07, 2023
Interaction Effect
Decreased International Normalized Ratio and anticoagulant effects
Interaction Summary
Concurrent administration of warfarin and ginseng decreased warfarin exposure, however thrombotic events have not been reported, in a clinical or research setting (n=20). In 2 separate case reports, ginseng was suspected to have caused a decrease in INR in patients previously stabilized on warfarin resulting in one case of thrombosis. . In vitro studies have shown ginseng components to inhibit platelet aggregation . The exact mechanism and extent of this interaction is not known; however, since ginseng was reported to cause an interaction in one randomized controlled trial and likely involved in the interaction with warfarin in human case reports, ginseng is best avoided in patients taking anticoagulants with narrow therapeutic ranges.
Severity
Moderate
Onset
Delayed
Evidence
Probable
How To Manage Interaction
Avoid ginseng use with warfarin if possible. If the patient elects to combine therapy, monitor PT/INR.
Mechanism Of Interaction
Unknown
Literature Reports
A) Peak international normalized ratio (INR) and peak plasma warfarin levels decreased, without any reported clotting events, in a randomized controlled trial of 20 healthy young adults. Patients received 5 mg of oral warfarin for three consecutive days during week one and week four, and were randomly assigned to receive either 1 gram of American Ginseng (Panax quinquefolius) or placebo twice daily from weeks two through four. Peak INR decreased by 0.16 and 0.02 on week four from week one (p=0.0012) in the ginseng group and the placebo group, respectively. Peak plasma warfarin level decreased by 0.2 and 0.0 (p=0.026) in the same 2 groups. Vitamin K intake did not differ between the 2 groups (p>0.2) .
B) A 47-year-old male stabilized on warfarin therapy for five years experienced a significant decrease in his International Normalized Ratio (INR) values following the initiation of Panax ginseng. Four weeks before he started ginseng, his INR was 3.1, which was consistent with his INR values for the previous nine months. Two weeks following the start of ginseng (Ginsana (R)) three times daily, his INR was 1.5. Ginseng was discontinued, and his INR returned to 3.3 in two weeks .
C) A 58-year-old man developed thrombosis in an aortic valve prosthesis, failing to maintain adequate International Normalized Ratio (INR) values after ingesting a commercial ginseng product (ginseng variant, dose and duration not specified) while receiving warfarin. Until 3 months prior to admission, the patient had been effectively maintained on warfarin anticoagulation, after which his INR values became unstable with recalcitrant sub-therapeutic values that required progressively larger doses of warfarin. Although the timing of the initiation of ginseng with warfarin was not specified, the author was unsuccessful in his search to find other potential causes of warfarin interference .
Warfarin Overview
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Warfarin is used to prevent blood clots from forming or growing larger in your blood and blood vessels. It is prescribed for people with certain types of irregular heartbeat, people with prosthetic (replacement or mechanical) heart valves, and people who have suffered a heart attack. Warfarin is also used to treat or prevent venous thrombosis (swelling and blood clot in a vein) and pulmonary embolism (a blood clot in the lung). Warfarin is in a class of medications called anticoagulants ('blood thinners'). It works by decreasing the clotting ability of the blood.
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Definitions
Severity Categories
Contraindicated
These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.
Major
This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.
Moderate
This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.
Minor
While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.
Onset
Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.
Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.
Evidence
Level of documentation of the interaction.
Established: The interaction is documented and substantiated in peer-reviewed medical literature.
Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.
How To Manage The Interaction
Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.
It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.
Mechanism Of Interaction
The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.
Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.
Where Does Our Information Come From?
Information for our drug interactions is compiled from several drug compendia, including:
The prescribing information for each drug, as published on DailyMED, is also used.
Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.
The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.