Healthcare professionals may recommend a 75–100 milligram (mg) dose of aspirin per day to help prevent heart attacks. A person can also take 160–325 mg during a heart attack.

Aspirin is a pain reliever that can thin the blood. Healthcare professionals may recommend aspirin to help prevent heart attacks. It may also be beneficial during or after a heart attack. But it is not suitable for everyone.

As such, it is important to speak with a healthcare professional before taking aspirin to prevent or manage a heart attack. They will consider each person’s risk profile before recommending if they should use aspirin.

This article describes the connection between aspirin and heart attacks. It explores who should take aspirin and how to take it during a suspected heart attack.

Later, it looks at who should avoid aspirin, the risks involved, and other daily ways to help prevent a heart attack.

An aspirin table, which may help prevent and treat heart attacks.Share on Pinterest
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Aspirin can help prevent heart attacks by making it more difficult for platelets in the blood to form clots.

Smoking and certain medical conditions, such as high blood pressure and diabetes, can cause plaques to form in the coronary arteries. Plaques are buildups of cholesterol, white blood cells, and other substances. Together, they form a waxy deposit that can collect in the walls of the arteries.

If parts of these plaques break off, they too can form blood clots. These can block arteries and reduce the blood flow to the heart, causing a heart attack.

Aspirin can help reduce the severity of a heart attack. However, as the American Heart Association note, aspirin alone cannot treat a heart attack.

Before taking an aspirin for a suspected heart attack, contact 911 or the local emergency number. The operator can advise whether to take aspirin and how much to take.

If the operator does not suggest aspirin, the person may receive it in the emergency department.

Learn more about what to do during a heart attack.


A person can take 160–325 milligrams (mg) of aspirin during a heart attack.

The United Kingdom’s National Health Service recommends chewing a 300-mg tablet of aspirin while waiting for the ambulance to arrive.

Uncoated aspirin is preferable, as it works faster, but a person can also chew an enteric-coated tablet if uncoated ones are unavailable.

A healthcare professional may prescribe a daily low dosage of aspirin to prevent heart attacks.

One 2019 study found that people who regularly took aspirin had a 14% reduced risk of experiencing a first heart attack. However, the same study cautions against the widespread use of aspirin for this purpose. This is because regularly taking aspirin may increase the risk of major bleeding problems by 46%.

Also, a 2020 study concluded that the potential benefits of aspirin are not the same for everyone. For example, the researchers found that regular aspirin use only reduced the chances of a first heart attack for some people who had an increased risk of cardiovascular disease.

People with this increased risk include those who:

So, while aspirin can help prevent a first heart attack for some people, this benefit may not be widespread.


If a healthcare professional prescribes aspirin as a preventive measure, they recommend 75–100 mg per day.

However, it is important to speak with a healthcare professional before taking this dosage. They will consider each person’s risk profile before making this recommendation.

Missed dose and overdose

If a person forgets a dose, they should take it as soon as they remember. But if it is nearly time for the next dose, skip the missed dose and continue with the regular schedule.

Anyone concerned that they may have taken too much aspirin should immediately call Poison Control, at 1-800-222-1222, or use its online resource. An expert will provide care instructions.

It can be useful to give the following information:

  • the person’s name and weight
  • the name of the product
  • when the person took it
  • how much they took

Aside from helping to thin the blood and relieve pain, aspirin may have other benefits.

For example, the National Cancer Institute notes that aspirin may have cancer-preventing properties, particularly for colorectal cancer.

People with an increased risk of cardiovascular disease and people aged 50–59 may benefit most from taking aspirin for this purpose.

However, the institute warns, for people aged 70 and above, a daily low dosage of aspirin may increase the likelihood of developing and dying from an advanced form of cancer.

The most common side effects of aspirin include indigestion and stomach pain, and bleeding or bruising more easily.

Some possible complications include:

There is a higher risk of certain side effects and complications. As the authors of research from 2021 report, Reye’s syndrome and brain hemorrhages are rare.

Rates of allergic reactions, they note, range from 1–2% in the general population but rise to 26% among people with asthma or chronic rhinosinusitis.

A low daily dosage of aspirin may not be suitable for everyone.

Speaking with a healthcare professional before taking aspirin every day may be especially important for people who:

  • have ever had an allergic reaction to aspirin
  • have asthma
  • have severe kidney or liver problems
  • have hemophilia or other bleeding conditions
  • have uncontrolled high blood pressure
  • are older than 65
  • are pregnant or nursing

The American College of Cardiology and the American Heart Association have collaborated on the following guidance, concerning daily aspirin to prevent heart attacks:

  • Low daily doses of aspirin may be safe for people aged 40–70 years who have no increased risk of bleeding.
  • But these doses are likely unsafe for people older than 70 and all people with an increased risk of bleeding.

People with this increased risk include those who have:

  • peptic ulcers
  • gastritis
  • a history of either issue, if they currently drink alcohol or take the blood thinner warfarin

Our daily routines can greatly affect our risk of cardiovascular disease. Beyond taking aspirin, there are several ways to reduce the likelihood of a heart attack.

Research from 2019, for example, highlights these approaches:

Aspirin is a blood thinner. It makes it difficult for the platelets in blood to form clots. This can help reduce the risk of a heart attack and limit the severity of one that occurs.

However, only take aspirin during a suspected heart attack if an emergency medical responder recommends it. It is important to contact emergency services first.

Taking aspirin regularly to prevent heart attacks carries risks for some people. Speak with a healthcare professional before taking aspirin every day, even a low dosage.