What are the complications of hemorrhage caused by warfarin and superwarfarin toxicity?

Updated: Jan 19, 2018
  • Author: Kent R Olson, MD, FACEP; Chief Editor: David Vearrier, MD, MPH  more...
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Bleeding is the primary adverse effect of warfarin and superwarfarin toxicity and is related to the intensity of anticoagulation, length of therapy, the patient's underlying clinical state, and use of other drugs that may affect hemostasis or interfere with warfarin metabolism. [9] Fatal or nonfatal hemorrhage may occur from any tissue or organ.

Children rarely ingest enough product to develop clinical evidence of anticoagulation. A study of 595 children younger than age 6 years who had ingested superwarfarin rodenticides found only 2 with elevated PTs (international normalized ratio [INR] 1.5 and 1.8), and neither had symptoms. [8]

Over the 20-year period from 1985-2004, the AAPCC’s Toxic Exposure Surveillance System (TESS) database reported no deaths in children younger than age 6 years after ingestion of superwarfarins and only one adult death due to unintentional ingestion. [10] Virtually all cases of severe hemorrhage occurred after intentional self-poisoning.

Minor bleeding from mucous membranes, subconjunctival hemorrhage, hematuria, epistaxis, and ecchymoses may occur.

Major bleeding complications include GI hemorrhage, intracranial bleeding, and retroperitoneal bleeding. Massive hemorrhage usually involves the GI tract but may involve the spinal cord or cerebral, pericardial, pulmonary, adrenal, or hepatic sites. Although rare, massive intraocular hemorrhage has been reported in patients with preexisting disciform macular degeneration.

In a population-based retrospective cohort study of patients aged 65 years or older with atrial fibrillation (AF) who underwent dialysis, warfarin was found to be associated with a 44% higher risk of bleeding and did not reduce the risk of stroke. [11]

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