Warfarin

DRUG INFORMATION

  ADULT
    - Post-Myocardial Infarction For high-risk patients with MI (e.g., those with a
      large anterior MI, those with significant heart failure, those with intracardiac
      thrombus visible on transthoracic echocardiography, those with AF, and those with
      a history of a thromboembolic event), therapy with combined moderate-intensity
      (INR, 2 to 3) warfarin plus low-dose aspirin (≤ 100 mg/day) for at least 3 months
      after the MI is recommended.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'dosage and
      administration', retrieved 2026-08-29
    - Dosing Recommendations without Consideration of Genotype If the patient’s CYP2C9
      and VKORC1 genotypes are not known, the initial dose of warfarin sodium tablets is
      usually 2 to 5 mg once daily.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'dosage and
      administration', retrieved 2026-08-29
    - Typical maintenance doses are 2 to 10 mg once daily.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'dosage and
      administration', retrieved 2026-08-29

  CHILD
    - Adequate and well-controlled studies with warfarin sodium have not been conducted
      in any pediatric population, and the optimum dosing, safety, and efficacy in
      pediatric patients is unknown. Pediatric use of warfarin sodium is based on adult
      data and recommendations, and available limited pediatric data from observational
      studies and patient registries.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'pediatric use',
      retrieved 2026-08-29

  RENAL IMPAIRMENT
    - Determinations of whole blood clotting and bleeding times are not effective
      measures for monitoring of warfarin sodium tablets therapy. 2.5 Renal Impairment
      No dosage adjustment is necessary for patients with renal failure.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'dosage and
      administration', retrieved 2026-08-29
    - ( 8.2 ) Renal Impairment: Instruct patients with renal impairment to frequently
      monitor their INR.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'use in specific
      populations', retrieved 2026-08-29
    - Consider lower initiation and maintenance doses of warfarin sodium in elderly
      patients [see Dosage and Administration ( 2.2 , 2.3 )] . 8.6 Renal Impairment
      Renal clearance is considered to be a minor determinant of anticoagulant response
      to warfarin.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'use in specific
      populations', retrieved 2026-08-29

  HEPATIC IMPAIRMENT
    - Instruct patients with renal impairment taking warfarin to monitor their INR more
      frequently [see Warnings and Precautions ( 5.4 )] . 8.7 Hepatic Impairment Hepatic
      impairment can potentiate the response to warfarin through impaired synthesis of
      clotting factors and decreased metabolism of warfarin.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'use in specific
      populations', retrieved 2026-08-29
    - If this drug is used during pregnancy, or if the patient becomes pregnant while
      taking this drug, the patient should be apprised of the potential hazard to a
      fetus [see Use in Specific Populations ( 8.1 )] .
      Source: US FDA label for warfarin (Warfarin Sodium), section 'warnings and
      cautions', retrieved 2026-08-29

  PREGNANCY   [ AVOID ]
    The label says not to use it. Read the quote below before deciding.
    - Risk Summary Warfarin sodium is contraindicated in women who are pregnant except
      in pregnant women with mechanical heart valves, who are at high risk of
      thromboembolism, and for whom the benefits of warfarin sodium may outweigh the
      risks [see Warnings and Precautions ( 5.7 )] .
      Source: US FDA label for warfarin (Warfarin Sodium), section 'pregnancy',
      retrieved 2026-08-29
    - Exposure to warfarin during the first trimester of pregnancy caused a pattern of
      congenital malformations in about 5% of exposed offspring.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'pregnancy',
      retrieved 2026-08-29
    - Because these data were not collected in adequate and well-controlled studies,
      this incidence of major birth defects is not an adequate basis for comparison to
      the estimated incidences in the control group or the U.S. general population and
      may not reflect the incidences observed in practice.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'pregnancy',
      retrieved 2026-08-29

  BREASTFEEDING
    - ( 8.1 ) Lactation: Monitor breastfeeding infants for bruising or bleeding.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'use in specific
      populations', retrieved 2026-08-29
    - Mental retardation, blindness, schizencephaly, microcephaly, hydrocephalus, and
      other adverse pregnancy outcomes have been reported following warfarin exposure
      during the second and third trimesters of pregnancy [see Contraindications ( 4 )]
      . 8.2 Lactation Risk Summary Warfarin was not present in human milk from mothers
      treated with warfarin from a limited published study.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'use in specific
      populations', retrieved 2026-08-29
    - Because of the potential for serious adverse reactions, including bleeding in a
      breastfed infant, consider the developmental and health benefits of breastfeeding
      along with the mother’s clinical need for warfarin sodium and any potential
      adverse effects on the breastfed infant from warfarin sodium or from the
      underlying maternal condition before prescribing warfarin sodium to a lactating
      woman.
      Source: US FDA label for warfarin (Warfarin Sodium), section 'use in specific
      populations', retrieved 2026-08-29