Can aspirin be administered to patients taking anticoagulants (blood thinners)?

Aspirin Should Be Suspended in Patients Taking Anticoagulants

For patients taking anticoagulants (blood thinners), aspirin should generally be suspended unless there is a specific high-risk indication such as recent acute coronary syndrome or coronary intervention. 1

Risk of Bleeding with Combined Therapy

• Combining aspirin with anticoagulants increases the risk of major bleeding without providing significant additional benefit in most clinical scenarios 1
• Evidence suggests that treating patients with anticoagulation plus aspirin increases the risk of major bleeding compared to anticoagulation alone (RR 1.26; 95% CI 0.92-1.72) 1
• The FDA drug label for aspirin specifically warns about increased bleeding risk when taken with anticoagulants 2
• Patients taking blood thinners are specifically listed as having a higher chance of stomach bleeding when taking aspirin 2

Specific Clinical Scenarios

Venous Thromboembolism (VTE)

• For patients with DVT or PE with stable cardiovascular disease who initiate anticoagulation and were previously taking aspirin, the American Society of Hematology suggests suspending aspirin for the duration of anticoagulation therapy 1
• This recommendation is based on evidence that continuing aspirin provides no additional benefit while increasing bleeding risk 1

Atrial Fibrillation

• For patients with atrial fibrillation on anticoagulation, aspirin combined with anticoagulant therapy has been associated with no reduction in stroke, systemic embolism, or myocardial infarction 3
• The risks associated with adding aspirin to anticoagulation in patients with AF outweigh the benefits in most cases 3

Coronary Artery Disease

• For patients with stable coronary artery disease, antiplatelet medications should be stopped no later than 12 months after the last percutaneous coronary intervention when anticoagulation is required 1
• Direct oral anticoagulants (DOACs) are preferred over warfarin in patients with stable coronary artery disease when an indication for anticoagulation is present 1

Exceptions - When to Continue Aspirin with Anticoagulation

• Recent acute coronary syndrome or coronary intervention (generally within 1-4 weeks) 1
• Patients with mechanical heart valves require lifelong aspirin (75-100mg/day) in addition to warfarin 1
• Patients at exceptionally high risk for stent thrombosis 1
• Triple therapy (aspirin + P2Y12 inhibitor + anticoagulant) should be reserved only for patients at the highest risk of thrombotic complications and should ideally not exceed 30 days 1

Practical Considerations

• When aspirin is required with anticoagulation, the dose should not exceed 100 mg 1
• For patients requiring both therapies, a proton pump inhibitor should be initiated prophylactically to reduce GI bleeding risk 1
• When targeting INR for patients on both warfarin and aspirin, a lower INR (2.0-2.5) might be reasonable to reduce bleeding risk 1
• A critical review of the indication for aspirin therapy is needed at the time anticoagulant therapy is initiated, weighing increased bleeding risk against potential cardiovascular benefits 1

Monitoring and Management

• Patients on combined therapy should be closely monitored for signs of bleeding, especially gastrointestinal bleeding 1
• For patients with mechanical heart valves on combined therapy, the INR should be at least 2.5 (based on type of prosthesis) 1
• In patients who must receive both therapies, the lowest effective dose of aspirin (75-100 mg) should be used to minimize bleeding risk 1, 4