Vitamin K antagonist (oral anticoagulant)
Warfarin dosage guide: how much to take and when
Choosing the right dose of Warfarin (Warfarin) is the most important practical decision after starting therapy. Warfarin is supplied as tablet in 1mg, 2mg, 2.5mg, 3mg, 4mg, 5mg, and the right dose for a given person depends on the indication, age, comorbidities and tolerance to the active ingredient Warfarin.
Starting dose and titration
According to the prescribing information, most adults begin Warfarin at the lowest available strength of 1mg, 2mg, 2.5mg, 3mg, 4mg, 5mg and titrate up only if symptom control is insufficient and tolerability is good. Higher doses are reserved for selected cases. Older adults, people with renal or hepatic impairment, and those taking interacting medications should usually start at the lowest dose.
When to adjust
Dose adjustment is guided by symptom response and side effect burden, not by arbitrary schedules. Warfarin inhibits vitamin K epoxide reductase complex 1 (VKORC1), the enzyme responsible for regenerating reduced vitamin K, a cofactor for the gamma-carboxylation of clotting factors II, VII, IX and… If side effects are limiting at a given dose, going down a step is usually preferred over stopping abruptly. If the response is incomplete after several weeks, a higher dose can be tried under medical supervision.
Frequently asked questions
What is the standard starting dose of Warfarin? ▾
Most adults start Warfarin at the lowest strength of 1mg, 2mg, 2.5mg, 3mg, 4mg, 5mg, with adjustment based on symptom response and tolerance. Older adults and those with reduced kidney or liver function generally start lower. The prescriber decides the exact starting dose for each person.
Can I take a higher dose of Warfarin if it isn't working? ▾
Higher doses of Warfarin should only be used after consulting the prescriber. Doubling on your own is unsafe, especially with active ingredients in the Vitamin K antagonist (oral anticoagulant) class. The prescriber can confirm whether titration is appropriate or whether the medication needs to be changed.
Products containing Warfarin
More on Warfarin
- With alcoholWarfarin and alcohol — is it safe to drink?
- With foodShould Warfarin be taken with food?
- Side effectsWarfarin side effects: common, rare and warning signs
- OnsetHow fast does Warfarin start working?
- DurationHow long does Warfarin last?
- Missed doseWhat to do if you miss a dose of Warfarin
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.