How could we improve it?

This article contains false or inaccurate information.

Please tell us what was incorrect.

Please note that you do not need to fill this detail if it's inconvenient for you. Click Send My Opinion below to continue reading our site.
This article doesn't provide enough info.

Please tell us what was missing.

Please note that you do not need to fill this detail if it's inconvenient for you. Click Send My Opinion below to continue reading our site.
Hmm... I have a question.

We’re unable to offer personal health advice, diagnosis, or treatment, but we welcome your feedback! Just type it in the box below.

If you're facing a medical emergency, call your local emergency services immediately, or visit the nearest emergency room or urgent care center.

Or copy link



Uses|Dosage|Directions|Side effects|Precautions/Warnings|Interactions


What is Aspir-81® (Acetylsalicylic Acid) used for?

Aspir-81® is commonly used for treating pain and reducing fever or inflammation. It is also used for primary prevention of thromboembolic disorders and cardiovascular events, such as ischemic stroke, transient ischemic attack, acute myocardial infarction, prevention of recurrent, unstable angina pectoris, chronic stable angina pectoris.

In addition, Aspir-81® is taken for secondary prevention of cardiovascular disease in persons with diabetes mellitus such as history of myocardial infarction, vascular bypass procedure, stroke or transient ischemic attack, angina and persons with additional risk factors, including hypertension, smoking, dyslipidemia, and family history of cardiovascular disease.

If you have recently had surgery on clogged arteries such as bypass surgery, carotid endarterectomy, coronary stent, your doctor may direct you to use aspirin in low doses as a blood thinner to prevent blood clots.

Aspir-81® may be prescribed for other uses; ask your doctor or pharmacist for more information.


The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using this medication.

What is the dose of Aspir-81® (Acetylsalicylic Acid) for an adult?

Ischemic stroke, transient ischemic attack:

  • Initial dose: 50-325mg once daily.
  • Maintenance dose: continue therapy indefinitely.

Acute myocardial infarction:

  • Initial dose: 160 mg as soon as acute myocardial infarction is suspected.
  • Maintenance dose: 160 mg a day for 30 days. After 30 days, consider further therapy based on dosage for the prevention of recurrent Acute myocardial infarction.

Prevention of recurrent MI, unstable angina pectoris and chronic stable angina pectoris, primary and secondary prevention of cardiovascular events in patients with Type 1 or Type 2 diabetes mellitus:

  • Initial dose: 75-325 mg once daily.
  • Maintenance dose: continue therapy indefinitely.

Coronary artery bypass graft (CABG):

  • Initial dose: 325 mg once daily starting 6 hours post-procedure.
  • Maintenance dose: continue therapy for 1 year post-procedure.

Percutaneous transluminal coronary angioplasty (PTCA):

  • Initial Dose: 325 mg given 2 hours pre-angioplasty.
  • Maintenance Dose: 160-325 mg once daily. Continue therapy indefinitely.

Carotid endarterectomy:

  • Initial Dose: 80 mg once daily to 650 mg twice daily, started pre-surgery.
  • Maintenance Dose: Continue therapy indefinitely.

Prevention of complications of pregnancy: pregnancy-induced hypertension, preeclampsia, intrauterine growth retardation, pregnancy with existing conditions (e.g., SLE, positive cardiolipin antibody test):

Initial dose: 80 mg daily from 13th-26th weeks of gestation.

What is the dose of Aspir-81® (Acetylsalicylic Acid) for a child?

The dosage has not been established in pediatric patients. It may be unsafe for your child. It is always important to fully understand the safety of the drug before using. Please consult with your doctor or pharmacist for more information.


How should I take Aspir-81® (Acetylsalicylic Acid)?

It comes as a tablet to take by mouth, with or without food, swallow tablet with a glass of water.

Do not chew, crush, or bite the enteric coated tablet.

Ask your health care provider any questions you may have about how to use medication.

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

It is also important to carry a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking with you in case of emergencies.

What should I do if I miss a dose?

If you miss a dose of Aspir-81®, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Side effects

What side effects can occur from Aspir-81® (Acetylsalicylic Acid)?

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

Aspir-81® may cause these side effects, such as:

  • Signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
  • Black, bloody, or tarry stools;
  • Coughing up blood or vomit that looks like coffee grounds;
  • Severe nausea, vomiting, or stomach pain;
  • Fever lasting longer than 3 days;
  • Hearing problems, ringing in your ears.

Less serious side effects may include:

  • Upset stomach;
  • Heartburn;
  • Drowsiness;
  • Headache.


What should I know before using Aspir-81® (Acetylsalicylic Acid)?

Consult with your doctor or pharmacist, if:

  • You are pregnant or breastfeeding. This is because, while you are expecting or feeding a baby, you should only take medicines on the recommendation of a doctor.
  • You are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • You have allergy with any of active or inactive ingredients of Aspir-81® or other medications.
  • You have a recent history of stomach or intestinal bleeding; liver disease; kidney disease; gout; or heart disease, high blood pressure, or congestive heart failure; a bleeding disorder such as hemophilia; or an asthma attack or severe allergic reaction after taking aspirin or an NSAID (non-steroidal anti-inflammatory drug) such as Advil, Motrin, Aleve, Orudis, Indocin, Lodine, Voltaren, Toradol, Mobic, Relafen, Feldene, and others.

Aspir-81® should not be given to a child or teenager who has a fever, especially if the child also has flu symptoms or chicken pox. Aspir-81® can cause a serious and sometimes fatal condition called Reye’s syndrome in children.

Is it safe in specific conditions (e.g. pregnancy, breastfeeding, or surgery)?


Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).


There are no adequate studies in women for determining risk when using this medication during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking this medication. This medication is pregnancy risk category C, D in 3rd trimester, according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk;
  • B=No risk in some studies;
  • C=There may be some risk;
  • D=Positive evidence of risk;
  • X=Contraindicated;
  • N=Unknown.


Aspir-81® and its metabolites pass into breast milk in small quantities. Since no adverse effects on the infant have been observed after occasional use, interruption of breastfeeding is usually unnecessary. However, on regular use or on intake of high doses, breastfeeding should be discontinued early.

Always consult your health care provider prior to using Aspir-81® if you are pregnant, breastfeeding.


What drugs may interact with Aspir-81® (Acetylsalicylic Acid)?

Aspir-81® may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

These product may interact with Aspir-81® include:

  • Mifepristone;
  • Acetazolamide;
  • Blood thinners (such as warfarin, heparin);
  • Corticosteroids (such as prednisone), methotrexate, valproic acid;
  • Herbal medications such as ginkgo biloba.

Does food or alcohol interact with Aspir-81® (Acetylsalicylic Acid)?

Aspir-81® may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

How do I store Aspir-81® (Acetylsalicylic Acid)?

Aspir-81® is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store Aspir-81® in the bathroom or the freezer. There may be different brands of Aspir-81® that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush Aspir-81® down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

How is Aspir-81® (Acetylsalicylic Acid) available?

Aspir-81® is available in the following dosage forms and strengths:

  • Aspir-81® mg is available in both Enteric Coated tablet formats.

Hello Health Group does not provide medical advice, diagnosis or treatment.


Aspirin 81. https://www.aspirin81.ca/en/product/facts/. Accessed October 14, 2016.

Aspir-81® (Acetylsalicylic Acid). http://www.webmd.com/drugs/2/drug-4843/aspir-81-oral/details#interactions. Accessed October 14, 2016.

Aspirin. http://reference.medscape.com/drug/zorprin-bayer-buffered-aspirin-343279#6.  Accessed October 14, 2016.

Picture of the author
Written by Stephanie Nicole Nera, RPh, PharmD on May 02, 2020
Medically reviewed by Stephanie Nicole Nera, RPh, PharmD