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Coumadin (Warfarin Sodium) - Summary



  • COUMADIN can cause major or fatal bleeding [see Warnings and Precautions (5.1) ].
  • Perform regular monitoring of INR in all treated patients [see Dosage and Administration (2.1) ].
  • Drugs, dietary changes, and other factors affect INR levels achieved with COUMADIN therapy [see Drug Interactions (7) ].
  • Instruct patients about prevention measures to minimize risk of bleeding and to report signs and symptoms of bleeding [see Patient Counseling Information (17) ].



COUMADIN (warfarin sodium) is an anticoagulant that acts by inhibiting vitamin K-dependent coagulation factors.

COUMADIN® is indicated for:

  • Prophylaxis and treatment of venous thrombosis and its extension, pulmonary embolism (PE).
  • Prophylaxis and treatment of thromboembolic complications associated with atrial fibrillation (AF) and/or cardiac valve replacement.
  • Reduction in the risk of death, recurrent myocardial infarction (MI), and thromboembolic events such as stroke or systemic embolization after myocardial infarction.

Limitations of Use

COUMADIN has no direct effect on an established thrombus, nor does it reverse ischemic tissue damage. Once a thrombus has occurred, however, the goals of anticoagulant treatment are to prevent further extension of the formed clot and to prevent secondary thromboembolic complications that may result in serious and possibly fatal sequelae.


See all Coumadin indications & dosage >>


Media Articles Related to Coumadin (Warfarin)

Genotyping Lowers Warfarin Risk in Hip or Knee Replacement
Source: Medscape Anesthesiology Headlines [2017.09.26]
Considering variants of three genes that affect response to warfarin improved the safety of using the drug.
Medscape Medical News

more news >>

Published Studies Related to Coumadin (Warfarin)

Genetics and the clinical response to warfarin and edoxaban: findings from the randomised, double-blind ENGAGE AF-TIMI 48 trial. [2015]
anticoagulant rather than warfarin... INTERPRETATION: CYP2C9 and VKORC1 genotypes identify patients who are more likely

Relationship between time in therapeutic range and comparative treatment effect of rivaroxaban and warfarin: results from the ROCKET AF trial. [2014]
CONCLUSIONS: The treatment effect of rivaroxaban compared with warfarin for the

Outcomes of temporary interruption of rivaroxaban compared with warfarin in patients with nonvalvular atrial fibrillation: results from the rivaroxaban once daily, oral, direct factor Xa inhibition compared with vitamin K antagonism for prevention of stroke and embolism trial in atrial fibrillation (ROCKET AF). [2014]
CONCLUSIONS: TI of oral anticoagulation is common and is associated with

Efficacy and safety of rivaroxaban compared with warfarin in patients with peripheral artery disease and non-valvular atrial fibrillation: insights from ROCKET AF. [2014]
CONCLUSION: Patients with PAD in ROCKET AF did not have a statistically

Apixaban vs. warfarin with concomitant aspirin in patients with atrial fibrillation: insights from the ARISTOTLE trial. [2014]
CONCLUSION: Apixaban had similar beneficial effects on stroke or systemic

more studies >>

Clinical Trials Related to Coumadin (Warfarin)

Role of Coumadin in Preventing Thromboembolism in Atrial Fibrillation (AF) Patients Undergoing Catheter Ablation [Completed]

Drug Interaction Study of Isavuconazole and Warfarin in Healthy Male Subjects [Completed]
The purpose of this study is to assess the effect of multiple doses of isavuconazole on the pharmacokinetics (PK) of warfarin after single dose administration.

Pharmacogenetics of Warfarin Induction and Inhibition [Completed]
This research study will help determine how a person's genetic makeup affects their response to drugs, the ability of the body to break down drugs, and their potential to experience an interaction between drugs. The investigators are investigating the drug interactions with the commonly used anticoagulant drug called warfarin. Warfarin is used for the treatment and prevention of life-threatening abnormal blood clots such as deep vein thrombosis, heart attacks, and strokes. The investigators chose warfarin for this study because it is a commonly used drug and must be monitored closely to avoid side effects. The investigators are interested in studying whether individuals with certain genetic profiles react differently to warfarin when it is combined with other drugs. This research is being done to see if certain genetic profiles require us to adjust warfarin doses differently than is needed for the general population. Genetic profiles of subjects are determined from their participation in the Pharmacogenetics Registry study (investigator Richard Brundage, University of Minnesota). The study hypothesis is: Functionally defective CYP2C9 alleles attenuate the warfarin-fluconazole inhibitory interaction and exacerbate the warfarin-rifampin inductive interaction.

Warfarin Adverse Event Reduction For Adults Receiving Genetic Testing at Therapy INitiation (WARFARIN) [Recruiting]
The WARFARIN Study is a clinical trial designed to determine if the use of genetic information related to warfarin sensitivity can help create a dose of warfarin that will result in less hospitalizations and deaths related to warfarin.

Genetic Response to Warfarin in Healthy Subjects [Completed]
The purpose of this study is to determine the importance of genetic differences on individuals' response to warfarin in a group of healthy subjects. Warfarin is also known by the "trade name" Coumadin and is in a class of medications called anticoagulants or "blood thinners." Warfarin works by reducing the blood's ability to make clots. It is used to stop blood clots from forming or growing larger in your blood and blood vessels. Warfarin is prescribed for many conditions, including for people with certain types of irregular heartbeat, people with replacement or mechanical heart valves, people who have suffered a heart attack, people who have had orthopedic surgery, or who have a history of having blood clots. Warfarin is used to prevent or treat deep vein thrombosis (swelling and blood clot in a vein), pulmonary embolism (a blood clot in the lung), and strokes (a blood clot in the brain). Researchers have found that certain genes may affect how a person's body will break down or react to warfarin. If genetic information can help doctors better determine the best dose of warfarin before it is first given, this may help the doctors get patients to the correct levels of blood thinning and thereby reduce the risk of bleeding or the risk of developing a blood clot. The expectation of this study is that this information will ultimately improve warfarin therapy while lessening the risks associated with dosing errors. This study is considered investigational because the subjects are healthy and not being prescribed warfarin for clinical care.

more trials >>

Reports of Suspected Coumadin (Warfarin) Side Effects

International Normalised Ratio Increased (352)Anaemia (219)Fall (123)Gastrointestinal Haemorrhage (107)Haemorrhage (102)International Normalised Ratio Decreased (90)Epistaxis (87)Pulmonary Embolism (79)Deep Vein Thrombosis (78)Rectal Haemorrhage (73)more >>


Based on a total of 6 ratings/reviews, Coumadin has an overall score of 5.50. The effectiveness score is 8.33 and the side effect score is 6.33. The scores are on ten point scale: 10 - best, 1 - worst. Below are selected reviews: the highest, the median and the lowest rated.

Coumadin review by 60 year old female patient

Overall rating:  
Effectiveness:   Highly Effective
Side effects:   Mild Side Effects
Treatment Info
Condition / reason:   dvt
Dosage & duration:   varied (dosage frequency: once a day) for the period of 6 mo.
Other conditions:   none
Other drugs taken:   none
Reported Results
Benefits:   The clots eventually completely dissolved over the course of the treatment.
Side effects:   I had to be careful shaving my legs. I had to pay attention to which foods and alcohol would alter my prothrombin time and make it necessary to take a higher or lower dosage, i. e. be sure to have the guacamole if I indulged in a margarita!
Comments:   After being diagnosed with thrombophlebitis and deep vein thrombosis twice - once in each leg - the first time through a veinogram and the second time through an ultrasound, I had 11 days in the hospital both times on IV heparin with complete bed rest while my clots which were in the saphenous vein all the way up to the femoral junction, were dissolving. After my release from the hospital I had 6 months of coumadin therapy. Through the years I have had sclerotherapy and infrared venous closure procedures. My vein disease has much improved except for capillary bruing/bleeding under the skin which would be considered more of a cosmetic problem, except that it bleeds in one spot that has come to my skin's surface when I bump it,scratch it, or hit it shaving.


Coumadin review by 61 year old male patient

Overall rating:  
Effectiveness:   Moderately Effective
Side effects:   Severe Side Effects
Treatment Info
Condition / reason:   heart murmer
Dosage & duration:   14.5 mg / day taken 1 per day for the period of continually
Other conditions:   none
Other drugs taken:   none
Reported Results
Benefits:   reduced risk of stroke
Side effects:   excesive bleeding
Comments:   14.5 mg daily


Coumadin review by care giver of 43 year old male patient

Overall rating:  
Effectiveness:   Considerably Effective
Side effects:   Extremely Severe Side Effects
Treatment Info
Condition / reason:   leg blood clot, dvt
Dosage & duration:   6mg taken daily for the period of 2months
Other conditions:   none
Other drugs taken:   none
Reported Results
Benefits:   The leg clot would not extend nor would other clots form, potentially causing death.
Side effects:   These were severe and included extreme and continuous nausea, feeling generally shitty (technical term employed by patient), no libido and inability to maintain erection during sex, orgasms that petered out and gave little pleasure, no overall energy for life. Patient decided to stop medication and try natural/alternative substance to thin the blood. this resulted in an extension of the clot and increased severity of pain, leading to emergency room visit and subsequent use of different blood thinner, syntron.
Comments:   Treatment included 2months of heparin injections in abdomen. Coumadin was given daily after the injections were stopped, at 6mg. The discontinuation of this medication caused an extension of the clot and re-admittance to hospital and another drug for blood thinning was given. Eventually, 6 months later, a doctor prescribed a compression stocking, which helped dramatically with swelling and pain. The Syntron blood thinner had no noticeable side-effects. Except possibly a still reduced libido.

See all Coumadin reviews / ratings >>

Page last updated: 2017-09-26

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