ASA for stroke and transient ischemic attack (TIA)

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ASA for stroke and transient ischemic attack (TIA)


Generic NameBrand Name
acetylsalicylic acid (ASA)Aspirin, Bufferin

How It Works

ASA is an antiplatelet medicine that decreases blood clot formation by preventing the smallest blood cells (platelets) from sticking together and forming blood clots.

Why It Is Used

ASA is the most commonly used medicine to prevent stroke. ASA reduces the risk of stroke in people who have already had a transient ischemic attack (TIA) or an ischemic stroke.

ASA or other antiplatelet drugs may reduce the risk of stroke in people who cannot have surgery to reopen a blocked carotid artery (carotid endarterectomy).

How Well It Works

ASA reduces the risk of stroke and heart attack or another transient ischemic attack (TIA).

ASA reduces the risk of death and the risk of dependence due to disability. And ASA increases the chance of recovery when it is given within 48 hours of an ischemic stroke that has been confirmed by a computed tomography (CT) scan to rule out hemorrhagic stroke.2

Side Effects

Side effects of ASA include:

  • Skin bruising, especially in older people.
  • Irritation of the stomach lining.
  • Bleeding from the digestive system.
  • Allergic reaction.
  • Bleeding (hemorrhage) in the brain (rare) or other internal organs of the body.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

A recent large study showed that ASA in doses of 75 mg to 150 mg daily is as effective as higher doses for long-term treatment.1

ASA can be started immediately during an ischemic stroke.

ASA may not always be helpful for people older than 75 or younger than 60 who do not have any risk factors for heart disease.

Safety tips when taking ASA

Follow these safety tips when taking ASA.

  • Take the medicine at the same time each day.
  • Take ASA with food to prevent irritation of the stomach.
  • Use buffered or enteric-coated ASA.
  • Check with your doctor before using other non-prescription drugs that contain ASA, such as Pepto-Bismol.
  • Be on the alert for signs of bleeding, and call your doctor immediately if any signs occur.
  • Let your doctor know if you are taking ASA and are planning to have surgery. You may have to stop the ASA temporarily.

Other medicines are available for people who cannot take ASA or for whom ASA is not effective. Clopidogrel (Plavix) is used for people who cannot take ASA or along with ASA therapy. Aggrenox is a medicine that combines ASA and extended-release dipyridamole in one medicine.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.



  1. Antithrombotic Trialists' Collaboration (2002). Collaborative meta-analysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high-risk patients. BMJ, 324(7329): 71–86.
  2. Alawneh J, et al. (2008). Stroke management, search date June 2007. Online version of BMJ Clinical Evidence:


By Healthwise Staff
Primary Medical Reviewer Anne C. Poinier, MD - Internal Medicine
Specialist Medical Reviewer Richard D. Zorowitz, MD - Physical Medicine and Rehabilitation
Specialist Medical Reviewer Donald Sproule, MD, CM, CCFP, FCFP - Family Medicine
Last Revised February 24, 2010

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