Warfarin interactions
Overview
Warfarin (Coumadin, Jantoven) is a blood thinner (anticoagulant). In our database it has 34 known interactions with common medicines and substances: 15 serious, 16 that need caution and 3 minor.
Avoid / serious 15 interactions
Two anticoagulants at onceAspirin
Higher risk of serious bleedingBismuth subsalicylate
Higher risk of serious bleedingCelecoxib
Higher risk of serious bleedingClopidogrel
Two types of blood thinnerDiclofenac
Higher risk of serious bleedingExcedrin
Higher risk of serious bleedingFluconazole
Can make warfarin much strongerIbuprofen
Higher risk of serious bleedingMeloxicam
Higher risk of serious bleedingMetronidazole
Can make warfarin much strongerNaproxen
Higher risk of serious bleedingRivaroxaban
Two anticoagulants at onceSt. John's wort
Can make your medicine stop workingSulfamethoxazole-trimethoprim
Can make warfarin much stronger
Use caution 16 interactions
Antibiotics can change warfarin's effectAmoxicillin-clavulanate
Antibiotics can change warfarin's effectAzithromycin
Antibiotics can change warfarin's effectCephalexin
Antibiotics can change warfarin's effectCiprofloxacin
Antibiotics can change warfarin's effectCitalopram
Higher bleeding riskDoxycycline
Antibiotics can change warfarin's effectDuloxetine
Higher bleeding riskEscitalopram
Higher bleeding riskFish oil
May add to bleeding riskFluoxetine
Higher bleeding riskLevofloxacin
Antibiotics can change warfarin's effectParoxetine
Higher bleeding riskSertraline
Higher bleeding riskTurmeric
May add to bleeding riskVenlafaxine
Higher bleeding risk
Minor 3 interactions
Regular acetaminophen can raise INRDayQuil
Regular acetaminophen can raise INRNyQuil
Regular acetaminophen can raise INR
No known interaction found
Our rules found no interaction between Warfarin and: Acyclovir, Albuterol, Alcohol, Allopurinol, Alprazolam, Amitriptyline, Amlodipine, Amphetamine salts, Aripiprazole, Ashwagandha, Atenolol, Atorvastatin, Baclofen, Birth control pills, Buprenorphine-naloxone, Bupropion, Buspirone, Caffeine, Calcium carbonate, Cannabis, Carvedilol, Cetirizine, Clindamycin, Clonazepam, Clonidine, Codeine, Colchicine, Creatine, Cyclobenzaprine, Dextromethorphan, Diazepam, Digoxin, Diphenhydramine, Doxylamine, Empagliflozin, Esomeprazole, Estradiol, Famotidine, Fexofenadine, Finasteride, Furosemide, Gabapentin, Glipizide, Grapefruit juice, Guaifenesin, Hydrochlorothiazide, Hydrocodone, Hydroxychloroquine, Hydroxyzine, Insulin, Iron supplements, Isotretinoin, Kratom, Lamotrigine, Levetiracetam, Levothyroxine, Lisdexamfetamine, Lisinopril, Lithium, Loperamide, Loratadine, Lorazepam, Losartan, Magnesium, Meclizine, Melatonin, Metformin, Methocarbamol, Methotrexate, Methylphenidate, Methylprednisolone, Metoprolol, Mirtazapine, Montelukast, Morphine, Naltrexone, Nicotine, Nitrofurantoin, Omeprazole, Ondansetron, Oseltamivir, Oxycodone, Pantoprazole, Paxlovid, Phentermine, Phenylephrine, Potassium supplements, Pravastatin, Prednisone, Pregabalin, Probiotics, Promethazine, Propranolol, Pseudoephedrine, Quetiapine, Rosuvastatin, Semaglutide, Sildenafil, Simvastatin, Spironolactone, Sumatriptan, Tadalafil, Tamsulosin, Tirzepatide, Tizanidine, Topiramate, Tramadol, Trazodone, Valacyclovir, Vitamin D, Zinc, Zolpidem.
Add at least two medicines, supplements or alcohol.
Sources
Source: FDA label for Warfarin on DailyMed (effective 2026-08), plus the labels of each interacting medicine.
This list covers the 147 medicines and substances in our database. It is not a complete list of every possible interaction. Always tell your doctor and pharmacist about every medicine, supplement and herbal product you take.