Dr HB LoIntegrative GP Blood thinner for AF · prep

If this is an emergency, don't use this tool — call 000 now. Signs of stroke (face drooping, arm weakness, slurred speech — think FAST), chest pain, trouble breathing, or heavy bleeding that won't stop: call 000 or go to your nearest emergency department.

Atrial fibrillation · blood thinners

Warfarin or the newer tablets? See the real trade-off — then decide it with your doctor.

If you've been told you have atrial fibrillation (AF) and a blood thinner is on the table, this lays the choice out the way a GP and cardiologist actually weigh it — and hands you the four questions that settle it in the room.

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Your situation Tell me what's going on — type it how you'd say it to a friend. One line is enough. The optional questions below sharpen it but are never required.

Tell me a little about your situation — newly diagnosed, already on a thinner, or just weighing it up?

Tap an example to fill it in

Optional — the things that actually decide it (all optional)

Do you have an artificial or replaced heart valve?

Have you been told you have kidney problems?

Any history that makes bleeding more likely?

Are you already taking a blood thinner?

If you're on warfarin — does your INR stay steady?

Does the cost of tablets matter for your decision?

Type a line above, or tap an example.

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Dr HB Lo — Integrative GP · drhblo.com · Warfarin vs DOAC comparison · generated

The real trade-off

This isn't ‘old drug vs new drug.’ It's one balance: a blood thinner lowers your stroke risk but raises your bleeding risk — and warfarin and the newer tablets (DOACs) sit differently on that balance. For most people with AF, an untreated year carries roughly a 2 in 100 or higher chance of stroke, and a blood thinner cuts that by about two-thirds — but the right one for you turns on a few specific things. Here are the two that decide it most often, and the four questions to settle it with your doctor.

Decider 1 Do you have a mechanical heart valve? → if yes, this changes everything (only warfarin is allowed).
Decider 2 Can your INR stay steady on warfarin? → unsteady INR is a common reason doctors look at a DOAC instead.

Side by side

How the two options differ — general information, not a recommendation.
Axis	Warfarin	Newer tablets (DOACs)
Stroke prevention	Effective, long-proven [1]	At least as effective; some at least as good or better [2]
Bleeding into the brain	Higher [2]	Lower — a key reason guidelines now usually prefer DOACs [1]
Stomach/bowel bleeding	Lower [2]	Can be higher with some DOACs [3]
Blood tests (INR)	Regular tests, dose adjusted [3]	Usually no routine INR testing [4]
Food & drug interactions	Many (diet, alcohol, other meds) [3]	Fewer, but still some [4]
Mechanical heart valve	Required — the only option [1]	Not allowed [1]
Kidney problems	Often usable [3]	Dose/eligibility depends on kidney function [3]
If you miss a dose / reversal	Reversible; long-acting [4]	Shorter-acting; reversal agents exist for some [4]

You told me you have a mechanical valve — see the highlighted “Mechanical heart valve” row above.

Most current Australian guidance prefers a DOAC for people who qualify — but “qualify” is the whole conversation, and your doctor decides it with you. CSANZ/NHFA 2018.

Three honest things

Three honest things this tool can't decide for you:

A blood thinner is not automatic. Whether you need one at all depends on your personal stroke risk score (your doctor calculates this — it's called CHA₂DS₂-VA). For some people the bleeding risk genuinely outweighs the benefit.
“Newer” is not always “better for you.” If you have a mechanical heart valve, or certain kidney problems, warfarin can be the safer or only choice. The modern tablet is not allowed with a metal valve.
No blood thinner is risk-free. Every option lowers stroke risk by raising bleeding risk. The decision is which trade-off fits your life and your body — that's a conversation, not a default.

You haven't told me about valves, kidneys or bleeding history — those three decide it most. Have your answers ready.

The four questions to ask

“What's my personal stroke risk score (CHA₂DS₂-VA), and does it mean a blood thinner is worth it for me?”
“Given my kidneys, any bleeding history, and any heart-valve issue — is warfarin or a DOAC the better fit for me, and why?”
“What's my bleeding risk on a blood thinner, and what would we do to lower it?”
“If I'm on warfarin now — is my INR steady enough, or is it worth reviewing my options?”

Take it with you

Email the one-page comparison to bring to your appointment.

A clean printable: the warfarin-vs-DOAC comparison, your situation, and the four questions — ready to hand to your GP.

Sent — check your inbox. Here's your comparison again so you can screenshot it now.

This is the general comparison. The full AF stroke-prevention kit works your exact numbers through — your stroke-risk score, your bleeding-risk score, and a side-by-side built around your situation — with the companion tools that show the real numbers.

→ CHA₂DS₂-VA risk tool · → HAS-BLED bleeding tool · → Cardiovascular decisions hub

Sources (Australian primary tier)

CSANZ / NHFA — National Heart Foundation of Australia & Cardiac Society of Australia and New Zealand: Australian Clinical Guidelines for the Diagnosis and Management of Atrial Fibrillation 2018, Heart, Lung and Circulation — heartlungcirc.org/article/S1443-9506(18)31778-5/fulltext
Australian Prescriber — Oral anticoagulation for adults with atrial fibrillation or venous thromboembolism — australianprescriber.tg.org.au/articles/oral-anticoagulation-for-adults-with-atrial-fibrillation-or-venous-thromboembolism.html
Australian Prescriber — Balancing the benefits and harms of oral anticoagulation in non-valvular atrial fibrillation — australianprescriber.tg.org.au/articles/balancing-the-benefits-and-harms-of-oral-anticoagulation-in-non-valvular-atrial-fibrillation.html
Australian Prescriber — Current management of atrial fibrillation — australianprescriber.tg.org.au/articles/current-management-of-atrial-fibrillation.html
healthdirect — Atrial fibrillation / Blood thinners — healthdirect.gov.au/atrial-fibrillation

eTG Complete (Therapeutic Guidelines) is the standing AU primary reference for AF anticoagulant selection and aligns with the above. Sources verified via WebSearch 2026-06-09. Pending clinical sign-off by Dr HB Lo before public indexing.