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Coumarin Plant Poisoning Follow-up

  • Author: Arasi Thangavelu, MD, FACEP, FAAEM; Chief Editor: Asim Tarabar, MD  more...
Updated: Mar 31, 2014

Further Outpatient Care

See the list below:

  • Hemodynamically stable adults who take warfarin therapeutically and who have an excessively elevated PT can be monitored closely as outpatients, provided they are in a safe environment and follow-up is arranged.
  • Young children who have accidentally ingested a small number of warfarin tablets or rodenticide pellets can be monitored on an outpatient basis. If concern exists regarding the dose, check PT at 24 and 48 hours.
  • Inadvertent exposures in adults without complications can be managed likewise.

Further Inpatient Care

Admit all patients with active bleeding or who have intentionally ingested these drugs. Avoid procedures that can precipitate hemorrhage (eg, nasogastric or endotracheal tubes, arterial punctures/line, central lines) unless necessary.


Inpatient & Outpatient Medications

Certain medications and/or foods interfere with warfarin levels in patients who are taking it for therapeutic purposes:

  • Ketoconazole: Due to the inhibition of warfarin metabolism by ketoconazole, patients taking high-dose ketoconazole concomitantly with warfarin may need their warfarin dosage reduced by more than is currently recommended, as well as receive more frequent INR monitoring.[3]
  • Levofloxacin: An increase in INR seems to occur when levofloxacin and warfarin are concomitantly administered; therefore, close monitoring of INR is advised.[4]
  • Cranberry, ginkgo biloba, glucosamine: Consumption of these led to an increase in INR values in a patient receiving warfarin.[5]
  • Antiretroviral therapy: INR should be monitored in patients receiving warfarin with concomitant highly active antiretroviral therapy (HAART) that includes either a protease inhibitor or an NNRTI.[6]
  • Coenzyme Q, ginseng, St. John’s wort: These have led to decreased warfarin levels and effects.

Patients should contact their doctor for a list of food and medications to avoid. They should notify their doctor if they are consuming any food or medications that are on the doctor’s list that might alter warfarin levels. The doctor might need to conduct dose adjustments for appropriate anticoagulation.



Consider for transfer any patient with life-threatening hemorrhage beyond the capabilities of your facility.



To prevent accidental childhood ingestions, rodenticide should be removed from areas where children have access.



Complications of hydroxycoumarin or rodenticide ingestion may include the following:

  • Complications of hemorrhagic shock (eg, end-organ ischemia, resulting in myocardial infarction or renal failure)
  • Intracranial hemorrhage
  • Complications of blood products (eg, infections, transfusion reactions)
  • Overcorrection of anticoagulation in a patient with medical indications for anticoagulation

Patient Education

Contributor Information and Disclosures

Arasi Thangavelu, MD, FACEP, FAAEM Consulting Staff, Department of Emergency Medicine, Archbold Memorial Hospital

Arasi Thangavelu, MD, FACEP, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine, Emergency Medicine Residents' Association, American College of Emergency Physicians

Disclosure: Nothing to disclose.


Lisandro Irizarry, MD, MPH, FACEP Chair, Department of Emergency Medicine, Wyckoff Heights Medical Center

Lisandro Irizarry, MD, MPH, FACEP is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American College of Medical Toxicology, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

John T VanDeVoort, PharmD Regional Director of Pharmacy, Sacred Heart and St Joseph's Hospitals

John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists

Disclosure: Nothing to disclose.

Chief Editor

Asim Tarabar, MD Assistant Professor, Director, Medical Toxicology, Department of Emergency Medicine, Yale University School of Medicine; Consulting Staff, Department of Emergency Medicine, Yale-New Haven Hospital

Disclosure: Nothing to disclose.

Additional Contributors

B Zane Horowitz, MD, FACMT Professor, Department of Emergency Medicine, Oregon Health and Sciences University School of Medicine; Medical Director, Oregon Poison Center; Medical Director, Alaska Poison Control System

B Zane Horowitz, MD, FACMT is a member of the following medical societies: American College of Medical Toxicology

Disclosure: Nothing to disclose.


Michael Hodgman, MD Assistant Clinical Professor of Medicine, Department of Emergency Medicine, Bassett Healthcare

Michael Hodgman, MD is a member of the following medical societies: American College of Medical Toxicology, American College of Physicians, Medical Society of the State of New York, and Wilderness Medical Society

Disclosure: Nothing to disclose.

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