Why You Should Take Aspirin If You're Having a Heart Attack

Early Aspirin Use Can Reduce Blood Clot Size

Man holding asprin

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If you have ever had a heart attack, a healthcare provider has probably told you to carry an aspirin or two with you at all times to have available if you ever think you might be having another heart attack. If your healthcare provider hasn’t told you to do this, they should have.

As it turns out, in the very earliest stages of a heart attack, in those critical minutes when part of your heart muscle is losing its blood supply, a simple aspirin can make a huge difference. It can mean the difference between a little heart damage and a lot of heart damage; it can mean the difference between living and dying.

Anyone who has had a heart attack in the past, or is known to be at risk for a heart attack in the future, should always carry a few aspirin with them.

Why Take an Aspirin While Waiting for the Paramedics

A heart attack, also called myocardial infarction (MI), is usually a form of acute coronary syndrome (ACS). ACS is triggered by the rupture of a plaque within a coronary artery. This plaque rupture causes a thrombus (blood clot) to form within the artery, leading to a blockage. The portion of the heart muscle being supplied by the artery then begins to die. The death of heart muscle is what defines a myocardial infarction.

What this means is that, at the time you are having a heart attack, a big part of the problem is the growth of a blood clot within the affected artery. Formation of this blood clot depends to a large extent on the blood platelets, which are tiny blood cells whose job is to participate in blood clotting.

Why Aspirin?

It turns out that aspirin—even in small doses—can rapidly and powerfully inhibit the activity of the platelets, and therefore can inhibit the growth of the blood clot. Inhibiting the growth of the blood clot is critical if you're having a heart attack since maintaining at least some blood flow through the coronary artery can keep heart muscle cells from dying.

Large randomized clinical trials have shown that if aspirin is used soon after the onset of an acute heart attack, the mortality rate after five weeks is reduced by as much as 23%.

Just as importantly, clinical trials have also strongly suggested that the early administration of aspirin can substantially reduce the size of the myocardial infarction, or convert a heart attack to unstable angina, or convert an ST-segment elevation myocardial infarction (STEMI) to a non-ST segment elevation myocardial infarction (NSTEMI). All of these benefits can greatly diminish the amount of heart damage you end up with, and (more importantly) can greatly diminish (or even eliminate) the long-term disabilities you’ll be dealing with.

This is why chewing and swallowing an aspirin is usually one of the first things you will be asked to do when you arrive in the emergency room with a suspected MI if you have not done so already.

Time is of the essence, and minutes count. So if you think you might be having a heart attack, most experts now advise dialing 911 immediately and having aspirin on hand so that you are able to take it if advised to do so by a medical professional.

By doing this, you may be able to begin treating a heart attack even before paramedics arrive.

How Much, What Type, and How to Take It

The current recommendation for people who may be having a heart attack is to chew and swallow one non-coated adult aspirin (325 mg) as soon as advised to do so by a medical professional. Chewing or crushing the aspirin gets it into your bloodstream more quickly—within four to five minutes—and researchers have measured a significant effect on platelets within that short period of time.

Swallowing a whole aspirin with water, as you normally would, takes 10 to 12 minutes to achieve the same effect. This time difference may seem small, but, once again, minutes count when your heart is at risk.

A Word From Verywell

Aspirin is effective in reducing the blood clots that are blocking a coronary artery during an acute heart attack. Anyone who has already had a heart attack, or who has an increased risk of having one in the future, should always carry a few non-coated adult aspirins with them. At the first sign of a heart attack, dial 911 and follow all emergency medical advice.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Nordt SP, Clark RF, Castillo EM, Guss DA. Comparison of three aspirin formulations in human volunteersWest J Emerg Med. 2011;12(4):381–385. doi:10.5811/westjem.2011.4.2222

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By Richard N. Fogoros, MD
Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology.