What's the starting lipitor dose with warfarin?

Short answer:
Start atorvastatin (Lipitor) at 10 mg once daily—just like you would for most patients—and then watch the INR closely. No special dose adjustment of warfarin is needed, but you’ll almost certainly have to tweak the warfarin dose a few times after you begin atorvastatin.

Why the 10 mg start?

Key point: No dose adjustment of warfarin itself is required at the start of atorvastatin. The interaction is mainly that statins can increase the INR (the measure of how thin the blood is). The magnitude of this effect varies, but it’s usually modest—enough to warrant a few INR checks, not a permanent dose shift.

How to monitor

If the INR climbs above target:

• Lower warfarin (usually 25–50 % reduction first, then fine‑tune).
• Re‑check in 3–5 days.

If the INR stays in range:

• You’re good.
• Consider whether you need to raise atorvastatin to hit your LDL goal.

Practical tips

1. Start low, go slow. 10 mg atorvastatin is the safest first step while you’re still titrating warfarin.
2. Inform the patient that they should watch for bruising or unusual bleeding and report it immediately.
3. Keep a medication log (both warfarin and atorvastatin) and share it with the lab.
4. Ask about other drugs that also affect INR (e.g., antibiotics, antifungals, other anticoagulants).
5. Consider alternatives if the patient is very sensitive to warfarin changes—some clinicians switch to a statin with less interaction risk (like pravastatin) or to a non‑warfarin anticoagulant (e.g., DOACs) if appropriate.

Bottom line

• Start atorvastatin at 10 mg daily.
• No special warfarin dose change is required at initiation.
• Check INR 2–4 days after starting, then every few days until it’s stable.
• Adjust warfarin only if the INR goes out of the therapeutic window.

That’s the safest way to manage the interaction while still giving your patient the cholesterol‑lowering benefit of Lipitor.