Warfarin Side Effects: Common, Serious & FDA Warnings

Common Side Effects of Warfarin

The most-reported reactions in the FDA Adverse Event Reporting System (FAERS) for warfarin. Percentages reflect the share of reports mentioning each reaction; a single report may include multiple reactions. Reports indicate co-occurrence, not causation.

Serious Outcomes and FDA Warnings

FAERS reports flagged with a serious outcome (death, hospitalization, life-threatening, disability, or congenital anomaly), plus reactions surfaced in the FDA-approved label's Warnings section. Reports indicate co-occurrence, not causation.

From the FDA-approved label, Section 5.1: Hemorrhage

Warfarin sodium can cause major or fatal bleeding. Bleeding is more likely to occur within the first month. Risk factors for bleeding include high intensity of anticoagulation (INR > 4), age greater than or equal to 65, history of highly variable INRs, history of gastrointestinal bleeding, hypertension, cerebrovascular disease, anemia, malignancy, trauma, renal impairment, certain genetic factors [see Clinical Pharmacology ( 12.5 )] , certain concomitant drugs [see Drug Interactions ( 7 )] , and long duration of warfarin therapy.

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Perform regular monitoring of INR in all treated patients. Those at high risk of bleeding may benefit from more frequent INR monitoring, careful dose adjustment to desired INR, and a shortest duration of therapy appropriate for the clinical condition. However, maintenance of INR in the therapeutic range does not eliminate the risk of bleeding. Drugs, dietary changes, and other factors affect INR levels achieved with warfarin sodium therapy. Perform more frequent INR monitoring when starting or stopping other drugs, including botanicals, or when changing dosages of other drugs [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 )] .

From the FDA-approved label, Section 5.4: Acute Kidney

Injury In patients with altered glomerular integrity or with a history of kidney disease, acute kidney injury may occur with warfarin sodium, possibly in relation to episodes of excessive anticoagulation and hematuria [see Use in Specific Populations ( 8.6 )] . More frequent monitoring of anticoagulation is advised in patients with compromised renal function.

Warfarin Recalls

FDA enforcement actions matched to warfarin via openFDA's structured generic_name field and the NDC bridge. Ongoing recalls are listed below (verify on FDA →); closed recalls are grouped in the disclosure that follows.

No recalls are on record for this drug in the FDA enforcement database.

Warfarin Shortages

FDA-listed shortages of warfarin products. Strength and dosage-form level detail.

Is Warfarin Safe?

Warfarin is FDA-approved. The label's Warnings and Precautions section covers hemorrhage (Section 5.1), tissue necrosis (Section 5.2), calciphylaxis (Section 5.3), acute kidney (Section 5.4), systemic atheroemboli and cholesterol microemboli (Section 5.5), limb ischemia, necrosis, and gangrene in patients with hit and hitts (Section 5.6), use in pregnant women with mechanical heart valves (Section 5.7), other clinical settings with increased (Section 5.8), endogenous factors affecting (Section 5.9).

As with any prescription, the assessment of safety is individual; consult a clinician about your own risk profile.

FDA-Approved Indications

Warfarin is FDA-approved for use in the condition categories below. The FDA-approved label’s Indications and Usage section is shown verbatim.

• Heart conditions
• Blood clots

Warfarin sodium tablets are 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 Warfarin sodium tablets have no direct effect on an established thrombus, nor does it reverse ischemic tissue damage.

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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. Warfarin sodium tablets are a vitamin K antagonist indicated for: Prophylaxis and treatment of venous thrombosis and its extension, pulmonary embolism ( 1 ) Prophylaxis and treatment of thromboembolic complications associated with atrial fibrillation and/or cardiac valve replacement ( 1 ) Reduction in the risk of death, recurrent myocardial infarction, and thromboembolic events such as stroke or systemic embolization after myocardial infarction ( 1 ) Limitations of Use Warfarin sodium tablets have no direct effect on an established thrombus, nor does it reverse ischemic tissue damage. ( 1 )

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