CPJE Secrets 2026: Warfarin Interactions

Warfarin Colors and Dosing (mg)

1 - Pink

2 - Lavender

2.5 - Green

3 - Tan

4 - Blue

5 - Peach

6 - Teal

7.5 - Yellow

10 - White

“Please Let Gary Tumnus Bring People To Your Wedding”

INR Goal

2-3

If below goal, increase dose by 5-15%

If above goal (>4), hold/decrease dose by 10-15%

If VERY high (>20), this is an overdose; treat with Vitamin K 10mg slow IV

Foods and Drugs that Increase INR/Bleed Risk

Foods and Herbs

4 Gs: ginger, gingko biloba, garlic grapefruit

Drugs

All anti-inflammatory agents

Pacerone (amiodarone)

Antibiotics: Bactrim, macrolides, Flagyl, fluoroquinolones, tetracyclines, neomycin

SSRIs

Antiplatelets

Azoles

Recommendation: decrease warfarin by 25-50%

Foods and Drugs that Decrease INR/Effect of Warfarin

Foods and Herbs

Ginseng

Green Tea

Soya

St. John’s Wort

Vitamin K and leafy green vegetables

Drugs

Barbiturates

Tegretol (carbamazepine)

Cholestyramine

Sandimmune

Oral contraceptives

Rifadin (rifampin) and similar products

Basically all inducers of CYP3A4

Medications with Unpredictable Effects on INR with Warfarin

Dilantin (phenytoin)

Cerebyx (fosphenytoin)