Should Aspirin Be Given Before Imaging Confirms Ischemic vs Hemorrhagic Stroke?
No—aspirin must NOT be given until brain imaging has excluded intracranial hemorrhage. This is an absolute requirement before any aspirin administration in acute stroke presentations. 1, 2, 3
Critical First Step: Imaging Before Aspirin
Brain imaging (CT or MRI) must be obtained first to exclude hemorrhagic stroke before any aspirin is administered. 1, 2, 3 This is a Class I, Level of Evidence A recommendation that applies universally to all acute stroke patients. 1, 3
- The risk of administering aspirin to a patient with unrecognized hemorrhagic stroke could be catastrophic, potentially expanding the hematoma and worsening outcomes. 2
- Even among 800 patients who were inadvertently given aspirin after hemorrhagic stroke in major trials, there was evidence of net hazard. 4
Once Hemorrhage Is Excluded: Immediate Aspirin Loading
After imaging confirms ischemic stroke (or excludes hemorrhage), give aspirin 160-325 mg immediately as a loading dose. 1, 2, 3
Specific dosing algorithm:
- Loading dose: 160-325 mg aspirin immediately after hemorrhage is ruled out 1, 2, 3
- Timing: Within 24-48 hours of symptom onset for maximum benefit 2, 3, 4
- Route: Oral if swallowing is safe (after dysphagia screening); rectal suppository (325 mg) or enteral tube (80 mg) if dysphagia is present 1
Evidence for early aspirin benefit:
- Aspirin reduces recurrent ischemic stroke by approximately 7 per 1000 patients during acute treatment 2, 4
- Reduces overall risk of further stroke or death by 9 per 1000 patients 4
- A higher loading dose (160-325 mg vs <160 mg) is associated with better functional outcomes (modified Rankin Scale ≤1) at discharge 5
Critical Contraindications After Imaging
Do not give aspirin if the patient is receiving or has received IV thrombolysis (tPA) within the past 24 hours. 1, 2, 3 This carries significantly increased risk of serious intracranial bleeding. 2, 3
Additional contraindications to verify:
- Active gastrointestinal bleeding 3
- Known aspirin allergy 3
- Patients on direct oral anticoagulants (DOACs) may need alternative strategies 1
Common Pitfalls to Avoid
Never use aspirin as a substitute for IV thrombolysis in eligible patients—aspirin is not an acute recanalization therapy and does not limit neurological consequences of the initial stroke. 2, 3
Never delay imaging to give aspirin empirically—the small absolute benefit of early aspirin (9 fewer events per 1000 patients) 4 is completely negated by the catastrophic risk of giving it to a hemorrhagic stroke patient. 2
Do not use dual antiplatelet therapy (aspirin plus clopidogrel) acutely in patients with left arm weakness/numbness of uncertain severity—this is only indicated for minor stroke (NIHSS ≤3-5) or high-risk TIA after hemorrhage is excluded. 1, 6 For moderate-to-severe strokes, bleeding risk outweighs benefit. 2
Risk-Benefit Context
While aspirin does increase hemorrhagic stroke risk by approximately 2 per 1000 patients 4, 7, this small risk is far outweighed by prevention of 7 recurrent ischemic strokes per 1000 patients 4—but only when hemorrhage has been definitively excluded by imaging first. 1, 2, 3