What is the recommended dosage of aspirin (acetylsalicylic acid) for cardiovascular protection and pain management?

Aspirin Dosing for Cardiovascular Protection

For cardiovascular protection, use aspirin 75-162 mg daily (typically 81 mg in the U.S.), as this dose range optimally balances efficacy with bleeding risk across all indications.

Acute Coronary Syndromes (ACS)

• Initial loading dose: 162-325 mg immediately when ACS is suspected or diagnosed, using non-enteric-coated formulation that should be chewed for rapid buccal absorption 1
• This loading dose should be administered even in patients already taking daily aspirin 1
• After the acute phase, transition to maintenance dosing of 81 mg daily, as higher maintenance doses (325 mg) provide no additional benefit but increase bleeding risk 1
• Following stent placement, 81 mg daily is the preferred maintenance dose rather than the previously recommended 325 mg, based on updated evidence showing equivalent efficacy with reduced bleeding 1

Secondary Prevention (Established Cardiovascular Disease)

• Aspirin 75-162 mg daily is strongly recommended for patients with prior MI, stroke, or established atherosclerotic cardiovascular disease, as benefits far outweigh bleeding risks 1, 2
• The ADAPTABLE trial demonstrated no difference in cardiovascular events or major bleeding between 81 mg and 325 mg daily in patients with established cardiovascular disease (38% had diabetes), confirming that lower doses are equally effective 1
• Use 81 mg daily as the standard maintenance dose to minimize gastrointestinal bleeding while maintaining full cardioprotective effects 1

Primary Prevention

High-Risk Patients (Ages 50-70 with Risk Factors)

• Aspirin 75-162 mg daily may be considered through shared decision-making for patients aged 50-70 years with diabetes and at least one additional major cardiovascular risk factor (family history, hypertension, smoking, dyslipidemia, or albuminuria) 1, 2
• The decision requires balancing individual bleeding risk against cardiovascular risk, as aspirin reduces vascular events by approximately 12% but increases gastrointestinal bleeding 1

Low-Risk Patients

• Aspirin is NOT recommended for men and women under age 50 with diabetes and no other major risk factors, as bleeding risks outweigh minimal cardiovascular benefits 1, 2
• Aspirin is NOT recommended for patients over age 70 years for primary prevention, as the ASPREE trial demonstrated increased major hemorrhage (HR 1.38) without cardiovascular benefit 1, 2

Contraindications

• Aspirin is contraindicated in individuals under age 21 due to Reye syndrome risk 1

Dosing Considerations Across All Indications

• The optimal dose range is 75-162 mg daily for long-term cardiovascular protection, with doses below 75 mg showing reduced efficacy 1
• Doses above 162 mg provide no additional cardiovascular benefit but significantly increase bleeding risk in a dose-dependent manner 1
• The CURE trial demonstrated major bleeding rates of 2.0% with <100 mg aspirin, 2.3% with 100-200 mg, and 4.0% with >200 mg daily 1
• In the U.S., the standard low-dose tablet is 81 mg, which represents the practical implementation of the 75-162 mg recommendation 1

Special Populations

Diabetes

• Despite concerns about "aspirin resistance" in diabetes patients measured by platelet function tests, clinical trials show no need for higher doses 1
• The hypothesis that patients weighing >70 kg require higher doses was not validated by the ASCEND trial 1
• Use standard 75-162 mg daily dosing regardless of diabetes status or body weight 1

Post-Stenting

• After coronary stenting, dual antiplatelet therapy (aspirin plus P2Y12 inhibitor) is indicated, with aspirin 81 mg daily as the preferred dose 1
• Duration of dual therapy depends on stent type and bleeding risk, requiring cardiovascular specialist input 1

Critical Pitfalls to Avoid

• Do not use enteric-coated aspirin for acute loading doses, as non-enteric formulations provide faster absorption when chewed 1
• Do not continue 325 mg daily long-term after the acute phase or post-stenting period, as this increases bleeding without improving outcomes 1
• Do not prescribe aspirin automatically for all diabetes patients—risk stratification is essential, particularly avoiding use in those under 50 or over 70 without established cardiovascular disease 1, 2
• Do not use doses below 75 mg daily, as efficacy is substantially reduced 1

Pain Management Context

While the question mentions pain management, the evidence provided focuses exclusively on cardiovascular indications. For analgesic purposes, aspirin doses typically range from 325-650 mg every 4-6 hours, which differs substantially from cardiovascular dosing. The cardiovascular protection doses (75-162 mg daily) are insufficient for pain relief.