Warfarin with Saw Palmetto Interaction Details
Brand Names Associated with Warfarin
- Coumadin®
- Jantoven®
- Warfarin
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 07, 2023
Interaction Effect
Increased risk of bleeding
Interaction Summary
Intraoperative bleeding was reported in a case of a patient taking saw palmetto. Two cases of increased INR have been reported in patients taking a combination of saw palmetto, pumpkin seed, and vitamin E (Curbicin(R)). One of the patients had been stable on warfarin prior to starting Curbicin(R). The other patient was not taking any concomitant anticoagulant therapy . Caution is advised.
Severity
Moderate
Onset
Delayed
Evidence
Theoretical
How To Manage Interaction
Caution is advised if saw palmetto is taken with warfarin. Monitor the INR and signs and symptoms of excessive bleeding.
Mechanism Of Interaction
Cyclooxygenase inhibition by saw palmetto
Literature Reports
A) Two cases of elevated international normalized ratio (INR) have been reported associated with taking pumpkin seed (cucurbita), saw palmetto, and vitamin E. A 61-year-old male taking warfarin with stable INR around 2.4 experienced an increased INR of 3.4 after 6 days of taking 5 tablets of Curbicin(R) daily, an herbal combination with pumpkin seed, saw palmetto, and vitamin E (10 milligrams per tablet). His INR returned to the therapeutic range within one week of stopping Curbicin(R). A 73-year-old male not on anticoagulant therapy experienced an INR of 2.1 during hospitalization for deterioration secondary to common cold. He had been taking Curbicin(R) 3 tablets daily for over one year. His INR improved (1.3 to 1.4) with vitamin K treatment, then normalized to 1 after stopping Curbicin(R) for one week .
B) A 53-year-old male taking saw palmetto developed brisk bleeding during a surgical procedure for resection of a brain tumor. In attempt to control the bleeding, the patient received 4 Liters of crystalloid fluids, 4 units of packed red blood cells, 3 units of pooled platelets, and 3 units of fresh frozen plasma. The procedure was prematurely terminated, and estimated blood loss was 2 Liters. Preoperative measures of prothrombin time (PT), activated partial thromboplastin time (aPTT), complete blood count, and blood chemistry were normal. No thromboprophylaxis was used prior to surgery. Postoperative PT and aPTT were normal; however, bleeding time was prolonged to 21 minutes (normal 2 to 10 minutes). Two days after surgery bleeding time remained prolonged at 14 minutes, which normalized over 5 days. Work-up for bleeding disorders was negative. The patient then disclosed his use of saw palmetto .
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.