Our Care

 

 

Drug Interactions

These drugs affect your INR (International Normalized Ratio) test, which measures how quickly your blood clots. We use the results of this test to determine how much Coumadin (warfarin) is in your system.

Contact Us
  • Lebanon, NH
    Phone: (603) 650-4123
  • Nashua, NH
    Phone: (603) 577-4200
  • The lower your INR value, the higher your risk of having a blood clot or stroke.
  • The higher your INR value, the higher your risk of bleeding and increased bruising.

Many drugs can affect how your body absorbs Coumadin, so it is very important to inform your anticoagulation provider of any changes in your medication routine.

Prescription drugs
Increased INR
  • Amiodarone
  • Anabolic Steroids
  • Antifungals
    • Fluconazole (diflucan)
    • Ketoconazole (nizoral)
    • Itraconazole (sporano)
  • Aspirin and Salicylates
  • Cephalosporins
  • Chloral Hydrate
  • Cimetidine (tagamet)
  • Clofibrate
  • Cranberry Juice (CYP2C9 inhibitor)
  • Danazol (danocrine)
  • Diflunisal (dolobid)
  • Disulfiram (Antabuse)
  • Fluvoxamine (Luvo)
  • Ginkgo Biloba
  • Heparin
  • Isoniazid (INH)
  • Erythromycin
  • Clarithromycin
  • Metronidazole (flagyl)
  • NSAIDS
  • Omeprazole (prilosec)
  • Paroxetine (paxil)
  • Pepto-Bismol
  • Quinilones
  • Tamoxifen
  • Tetracycline
  • Synthroid (thyroxine)
  • Ticlopidine (ticlid)
  • Trimethoprim-Sulfate (bactrim, Septra)
  • Vitamin E
  • Levaquin
Decreased INR
  • Barbiturates
  • Carbamaziepine (tegretol)
  • Oral contraceptives
  • Rifampin
  • Vitamin K
  • American Ginseng
May increase or
decrease INR
  • Allopurinol
  • Corticosteroids (Prednisone)
  • Penicillin
  • Phenytoin (dilantin)
Over the counter drugs
Increased INR
  • Aspirin / Bayer / Excedrin
  • Tylenol (more than twice daily)
  • Advil / Motrin / Ibuprofen
  • Pepto-Bismol
  • Pepcid A.C.
  • Zantac
  • Alka-Seltzer
  • Nyquil
  • Thera-Flu
  • Benadryl
  • Tylenol PM
  • Chondroitin; Glucosamine
Decreased INR
  • Green Tea
No effect
  • Mylanta
  • Tums
  • Imodium A.D.
  • Robitussin
  • Psuedophedrine / Sudafed
  • Tylenol (less than twice daily)