Does my daily aspirin therapy dose or pill coating matter?

Q. I have heart disease, and I take aspirin to reduce my risk of new heart problems. Does it matter how much aspirin I take, or whether the aspirin is the type that is "enteric-coated" to protect my stomach?

A. What we know for sure is that people who have heart disease reduce their risk of developing new heart problems by taking aspirin. So, I'm glad you're taking aspirin. But the best dose, and whether the enteric-coated form is better, are uncertain.

People with heart disease benefit from taking aspirin because aspirin makes the blood a bit less likely to clot and also reduces inflammation. Heart attacks typically happen because a blood clot has formed in one of the arteries of the heart, blocking the flow of blood to part of the heart muscle. Inflammation inside of plaque deposits in the walls of the arteries make such clots more likely to happen. So, theoretically, aspirin should benefit people with heart disease — and studies definitively show that it does.

However, aspirin also increases the risk of bleeding. The most common site of bleeding is the gastrointestinal tract, particularly the stomach and intestines. The enteric-coated form of aspirin was created to try to protect the stomach from bleeding. The most dangerous site of bleeding is inside the brain: a hemorrhagic stroke. Fortunately, the studies that show aspirin benefits people with heart disease also show that these benefits are greater than the risks of bleeding.

So, to your question, what dose of aspirin is best, and should you take an enteric-coated or uncoated aspirin pill? A 2023 study in JAMA Cardiology provides some insight. Over 10,000 people with heart disease were assigned, at random, to take either a regular-dose aspirin (325 mg) or a low-dose aspirin (81 mg) every day for about two years. While the dose was assigned at random, the study participants were allowed to choose whether they would take enteric-coated or uncoated aspirin.

The study concluded that neither the dose nor the enteric coating affected either the benefit or the risk from aspirin: there was not a statistically significant difference. However, in my opinion the study does not really settle the question. As big as it was, it was not big enough to have the statistical power needed. Also, it would have been better if participants had been assigned at random to enteric-coated or uncoated aspirin, and followed for more than two years. In particular, the study did observe a greater tendency for gastrointestinal bleeding in the uncoated aspirin groups.

In my opinion, this study and others indicate that people with heart disease probably should take one low-dose, enteric-coated aspirin pill a day. Like you, I have heart disease, and that's what I do.

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