Warfarin Dosing Chart
Please tick regimen used
Loading Regimen (Day 1-4) B
Loading Regimen (Day 1-4) A
only to be used if one or more risk factors
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Age ≥ 75 years
Slow AF
AF on discharge
All Indications
Surgery for Mitral Stenosis
Previous warfarin dose ≤3mg
nhancing drug
E
Warfarin dose
Warfarin dose
INR
INR
(mg)
(mg)
Day 1
Day 1
<1.4
10
<1.4
5.0
Day 2
<1.8
10
Day 2
<1.8
5.0
1.8
0.5
1.8
1.0
>1.8
0.5
>1.8
0.5
Day 3
<2.0
10
Day 3
<2.0
5.0
2.0 – 2.1
5.0
2.0 – 2.1
4.0
2.2 – 2.3
4.5
2.2 – 2.3
3.5
2.4 – 2.5
4.0
2.4 – 2.5
3.0
2.6 – 2.7
3.5
2.6 – 2.7
2.5
2.8 – 2.9
3.0
2.8 – 2.9
2.0
3.0 – 3.1
2.5
3.0 – 3.1
1.5
3.2 – 3.3
2.0
3.2 – 3.5
1.0
3.4
1.5
3.6 – 4.0
0.5
3.5
1.0
>4.0
0
3.6 – 4.0
0.5
>4.0
0
Day 4
<1.4
7.5
Day 4
<1.4
10
1.4
7.0
1.4
8.0
1.5
6.5
1.5
7.5
1.6 – 1.7
6.0
1.6 – 1.7
7.0
1.8
5.5
1.8
6.5
1.9
5.0
1.9
6.0
2.0 – 2.1
4.5
2.0 – 2.1
5.5
2.2 – 2.3
4.0
2.2 – 2.3
5.0
2.4 – 2.6
3.5
2.4 – 2.6
4.5
2.7 – 3.0
3.0
2.7-2.9
4.0
3.1 – 3.5
2.5
3.1 – 3.5
3.5
3.6 – 4.0
2.0
3.6 – 4.0
3.0
4.1 – 4.5
miss one day then 1mg
4.1 – 4.5
miss one day then 2mg
>4.5
miss 2 days then 0.5mg
>4.5
miss 2 days then 1mg
To calculate Maintenance Dose
Follow day 4 dose from day 5 onwards. Daily INR is essential for the first 2 weeks
WARFARIN - Tackling excessive warfarin-induced anticoagulation with no or minor bleeding e.g
haematuria, epistaxis
INR >4.5
Reduce dose or withdraw warfarin for 1–2
days and review.
INR > 5.0
Stop 1-2 days
INR >8.0
Give 0.5-1.0mg Vitamin K orally, repeat INR
in 24-48 hours
INR >8.0 with minor haemorrhage (e.g.
Give 0.5-2.0mg Vitamin K orally, repeat INR
epistaxis, haematuria)
in 24 hours
Patients with artificial heart valve – contact
haematology
In cases of major bleeding- contact haematology registrar on bleep 6068