What are the guidelines for aspirin (acetylsalicylic acid) dosage and usage?

Aspirin Dosage and Usage Guidelines

For cardiovascular disease prevention and treatment, aspirin should be dosed at 75-100 mg daily for most indications, with a loading dose of 162-325 mg in acute settings. This recommendation is based on the most recent and highest quality evidence that balances cardiovascular benefit against bleeding risk.

Primary Prevention Guidelines

High Cardiovascular Risk Individuals

• Recommendation: Aspirin 75-162 mg/day may be considered for primary prevention in adults at increased cardiovascular risk 1
• Target population:
  • Adults with diabetes aged ≥50 years with at least one additional major risk factor (family history of premature ASCVD, hypertension, dyslipidemia, smoking, or albuminuria) 1
  • Adults with 10-year cardiovascular risk ≥10% 1
• Risk assessment: Calculate 10-year ASCVD risk using validated risk calculators
• Contraindications: Increased bleeding risk, aspirin allergy, recent gastrointestinal bleeding, concurrent anticoagulant therapy, clinically active hepatic disease 1

Low Cardiovascular Risk Individuals

• Recommendation: Aspirin is NOT recommended for primary prevention in low-risk individuals 1
• Specifically: Not recommended for men and women aged <50 years with diabetes with no additional risk factors 1
• Rationale: Benefits likely outweighed by bleeding risks 1

Secondary Prevention Guidelines

Established Cardiovascular Disease

• Recommendation: Aspirin 75-162 mg/day is strongly recommended 1
• Target population: Patients with history of atherosclerotic cardiovascular disease, including:
  • Prior myocardial infarction
  • Prior stroke or TIA
  • Established coronary artery disease
  • Peripheral arterial disease

Acute Coronary Syndromes

• Loading dose: 162-325 mg (chewed for faster absorption) 1
• Maintenance dose: 75-100 mg daily 1
• Duration: Indefinite for secondary prevention 1

Dual Antiplatelet Therapy

• Recommendation: Aspirin 75-100 mg daily plus a P2Y12 inhibitor 1
• Duration:
  • 12 months after acute coronary syndrome 1
  • 6-12 months after percutaneous coronary intervention with drug-eluting stent 1

Special Considerations

Aspirin Alternatives

• For aspirin allergy: Clopidogrel 75 mg daily 1
• For high bleeding risk: Consider shorter duration of dual antiplatelet therapy while maintaining the 75-100 mg aspirin dose 2

Bleeding Risk Management

• Assess bleeding risk before initiating therapy
• Consider proton pump inhibitors in patients at high risk for gastrointestinal bleeding 2
• Monitor for signs of bleeding at each clinical visit 2

Dosing Rationale

Low-dose aspirin (75-100 mg daily) is as effective as higher doses for cardiovascular prevention while minimizing bleeding risk 1. The 2025 ACC/AHA guidelines specifically state that 75-100 mg daily exceeds the minimal effective dose required for platelet thromboxane A₂ suppression while allowing for interindividual variability in drug response 1.

Common Pitfalls to Avoid

1. Using excessive doses: Higher doses (>325 mg) increase bleeding risk without providing additional cardiovascular protection 2, 3
2. Inappropriate primary prevention: Prescribing aspirin to low-risk individuals where harm may outweigh benefit 1
3. Abrupt discontinuation: Can trigger rebound thrombotic events in patients with established cardiovascular disease 2
4. Overlooking contraindications: Failing to assess bleeding risk before initiating therapy 1
5. Neglecting comprehensive risk management: Aspirin should be an adjunct to, not a replacement for, management of other cardiovascular risk factors 1

By following these evidence-based guidelines for aspirin dosage and usage, clinicians can optimize the balance between cardiovascular protection and bleeding risk for their patients.