Coumarin Plant Poisoning Follow-up

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