Warfarin initiation dosing

Flexible Initiation Method

  • This nomogram is useful in hospitalized patients in whom INR can be checked on a daily basis.
  • Several studies have confirmed that 5mg initiation achieves therapeutic anticoagulation as rapidly as 10mg initiation but with a lower frequency of supra-therapeutic INRs.
  • The 10mg initiation nomogram should only be used in relatively young and healthy patients who are likely to be insensitive to warfarin, or in patients taking concurrent medications known to induce warfarin metabolism.
  • Please note that loading doses of warfarin are NOT RECOMMENDED.
    5mg Initiation 10mg Initiation
Day INR Dose Dose
1 - 5mg 10mg
2 <1.5 5mg 7.5-10mg
1.5-1.9 2.5mg 2.5mg
2-2.5 1-2.5mg 1-2.5mg
>2.5 0 0
3 <1.5 5-10mg 5-10mg
1.5-1.9 2.5-5mg 2.5-5mg
2-2.5 0-2.5mg 0-2.5mg
2.5-3 0-2.5mg 0-2.5mg
>3 0 0
4 <1.5 10mg 10mg
1.5-1.9 5-7.5mg 5-7.5mg
2-3 0-5mg 0-5mg
>3 0 0
5 <1.5 10mg 10mg
1.5-1.9 7.5-10mg 7.5-10mg
2-3 0-5mg 0-5mg
>3 0 0
6 <1.5 7.5-12.5mg 7.5-12.5mg
  1.5-1.9 5-10mg 5-10mg
  2-3 0-7.5mg 0-7.5mg
  >3 0 0