Laura Gottschalk, PhD, Sasha Milbeck, & Meg Seymour, PhD
A typical low-dose of aspirin (sometimes called “baby” aspirin) is 81mg, and many American adults take it daily with the hope that it will prevent heart disease and possibly cancer. The most recent data indicates that in 2017, 23% of U.S. adults over 40 who did not have heart disease took aspirin in order to help prevent developing it.1 About 23% of people taking aspirin daily reported that they did so without a doctor recommending it to them. Should you be taking aspirin for the prevention of heart disease? The recommendations depend on your age, as well as other risk factors.
In April 2022, the United States Preventive Services Task Force (USPSTF) issued their updated recommendations against people over 60 starting to take low-dose aspirin, because the benefits do not outweigh the risks.2 For those ages 40-59 with a 10% or more chance of developing heart disease over the next 10 years, the USPSTF notes that the data are unclear and so the decision to start taking low-dose aspirin should be an individual choice made with one’s physician, weighing the risks (which vary among individuals) against the small benefit.
These recommendations are notably different from the USPSTF’s 2016 recommendations, which did not recommend against starting to take aspirin for those ages 60-69. The 2016 recommendations also recommended adults ages 50-59 with a 10% or more chance of developing heart disease over the next 10 years and who were willing to take the aspirin daily for those 10 years begin to do so.3
What Are the Benefits and Risks?
Why have the recommendations changed over time, and what do we now know about the cardiovascular benefits of taking low-dose aspirin that we didn’t know a few years ago? A 2019 study combined the results of 13 clinical trials, all comparing aspirin to placebo or to no treatment.4 The combination study, called a meta-analysis, analyzed over 164,00 patients, who were followed for an average of 5 years. The researchers found that patients who used daily aspirin had fewer heart attacks and fewer ischemic strokes. However, the authors also found that people who took daily aspirin were more likely to have intracranial bleeding (inside the skull) and major gastrointestinal bleeding.
The USPSTF reviewed the research on low-dose aspirin in order to develop their recommendation, and drew similar conclusions.5 Their analysis of over 161,00 patients found that people taking daily aspirin reduced the risk of major cardiovascular events, but that risk reduction is only 2.5% fewer chances of having at least one cardiovascular event, such as heart attacks or stroke. And yet, the analysis also found that people taking aspirin were not less likely to die from heart attacks or strokes. In addition, people taking daily aspirin were 1% more likely to experience major bleeding, such as gastrointestinal bleeding that resulted in a transfusion, hospital admission, intracranial bleeding, or death.
It is important to know who is most likely to experience harmful bleeding. Research has shown that the increased chances of bleeding begins relatively soon after starting to take aspirin on a daily basis, and it increases with age. Bleeding is more common among men, smokers, people with high blood pressure, people with liver disease, people with diabetes, and people with a history of gastrointestinal problems, such as peptic ulcer disease.5 Taking certain medications can also increase the risk of bleeding, including nonsteroidal anti-inflammatory drugs (such as Ibuprofen or naproxen), steroids (such as prednisone), and anticoagulants (such as warfarin). We agree with the USPSTF recommendation that these factors make dangerous bleeding more likely for anyone taking daily aspirin.
According to the USPSTF, the benefits of aspirin use are different for someone in their 60s or 70s who has already been taking aspirin compared to someone in their 60s or 70s who is considering whether to start to take aspirin. For people already taking daily aspirin, the benefits become smaller with age, because the chance of serious bleeding increases with age. Modeling data suggest it may be a good choice to consider stopping taking regular aspirin after around 75. However, stopping daily aspirin can lead to a “rebound” effect where the chances of cardiovascular events increases slightly within the first few weeks that is maintained for at least one year.6 The increased risk means that about 1 additional patient out of every 74 patients (1.4%) who discontinue use will experience a cardiovascular event, such as heart attack or stroke. The risk is higher than 1.4% for people who previously had a CVD event and lower for those who took aspirin to prevent a first CVD event.7 If you are currently taking aspirin and are considering stopping, speak with your doctor about how to safely taper your use.
Does Daily Aspirin Prevent Cancer?
The USPSTF also reviewed scientific studies of whether daily low-dose aspirin can help prevent colorectal cancer. They found that four studies following patients for up to 10 years found no evidence that taking aspirin reduced the chances of developing colorectal cancer.5
The 2019 paper mentioned above also found that daily aspirin did not reduce the chances of dying of cancer, compared with no aspirin.4 In fact, one clinical trial in that meta-analysis (called ASPREE: Aspirin in Reducing Events in the Elderly) found that individuals who took aspirin were slightly more likely to die from cancers. Researchers analyzed the overall chance of dying from 14 common cancers, including colorectal cancer, and found that 3.1% of the participants taking aspirin had died a cancer-related death at 5 years follow-up, compared with 2.3% of those taking a placebo.8 This is a small difference, but is it conclusive? Most participants in the ASPREE trial had never used low-dose aspirin regularly before joining the study, and that made it impossible to determine if taking low-dose aspirin regularly for many years is likely to increase or decrease the chances of dying of cancer.
However, a more recent, longer-term study, published in 2021 found that people who started using low-dose aspirin regularly at a younger age and who continued after age 70 were less likely to develop colorectal cancer than people who didn’t use low-dose aspirin.9 That study combined 2 large studies that included almost 95,000 patients.
The USPSTF 2022 analysis notes that the evidence about aspirin and colorectal cancer is highly variable, with randomized clinical trials showing no benefit and some long-term observational studies showing some possible benefit.10 Given these inconsistent results, the USPSTF does not recommend that older patients begin taking low-dose aspirin for the sole purpose of preventing colorectal cancer.
The Bottom Line: Should I Take a Daily Aspirin?
Overall, the choice to begin taking aspirin (or to continue if you are already taking it) should be a decision that you make with your healthcare provider, after weighing the potential risks and benefits. The research described above is a good reminder that aspirin is a drug that has risks even at low doses. For many people, aspirin’s risk of serious bleeding may outweigh the benefits of decreased cardiovascular events. However, if you have been taking daily aspirin, stopping to take it also has risks, especially if you previously had a cardiovascular event such as a heart attack or stroke. When discussing with your healthcare provider the possibility of taking daily aspirin, let them know:
- Your medical history and all the medicines you are currently using, whether they are prescription or over-the-counter,
- Any allergies or sensitivities you may have to aspirin, and
- Any vitamins or dietary supplements you are currently taking
To read our comments made to the USPSTF about their 2021 updates to their recommendation statement, click here.
Other Ways to Prevent Heart Disease and Cancer
In 2019, heart disease and cancer were the leading causes of death in adults in the United States.
To reduce your risk of heart disease, don’t smoke, keep your cholesterol and blood pressure under control, and do what you need to do to prevent diabetes. Being a man and being older also put you at risk, but those are factors you can’t control.
To reduce your risk of colorectal cancer, don’t smoke, don’t drink alcohol in excess, have a healthy diet, stay physically active, and maintain a healthy weight. Being older, and having a family history of colon cancer, Crohn’s disease, or ulcerative colitis are the risk factors you can’t control.
All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.
The National Center for Health Research is a nonprofit, nonpartisan research, education and advocacy organization that analyzes and explains the latest medical research and speaks out on policies and programs. We do not accept funding from pharmaceutical companies or medical device manufacturers. Find out how you can support us here.
- O’Brien CW, Juraschek SP, Wee CC. Prevalence of aspirin use for primary prevention of cardiovascular disease in the United States: results from the 2017 National Health Interview Survey. Annals of Internal Medicine. 2019 Oct 15;171(8):596-8.
- Final Recommendation Statement: Aspirin Use to Prevent Cardiovascular Disease: Preventive Medication. https://uspreventiveservicestaskforce.org/uspstf/draft-recommendation/aspirin-use-to-prevent-cardiovascular-disease-preventive-medication. April 26, 2022
- Final Recommendation Statement: Aspirin Use to Prevent Cardiovascular Disease and Colorectal Cancer: Preventive Medication. https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/aspirin-to-prevent-cardiovascular-disease-and-cancer. April 11, 2016.
- Zheng SL, Roddick AJ. Association of aspirin use for primary prevention with cardiovascular events and bleeding events: a systematic review and meta-analysis. JAMA. 2019;321(3):277-87.
- Guirguis-Blake JM, Evans CV, Perdue LA, Bean SI, Senger CA. Aspirin Use to Prevent Cardiovascular Disease and Colorectal Cancer: An Evidence Update for the U.S. Preventive Services Task Force. Evidence Synthesis No. 211. Rockville, MD: Agency for Healthcare Research and Quality; 2021. AHRQ publication no. 21-05283-EF-1.
- Maulaz AB, Bezerra DC, Michel P, Bogousslavsky J. Effect of discontinuing aspirin therapy on the risk of brain ischemic stroke. Archives of Neurology. 2005; 62(8):1217-20.
- Sundström J, Hedberg J, Thuresson M, Aarskog P, Johannesen KM, Oldgren J. Low-dose aspirin discontinuation and risk of cardiovascular events: a Swedish nationwide, population-based cohort study. Circulation. 2017; 136(13):1183-92.
- McNeil JJ, Nelson MR, Woods RL, Lockery JE, Wolfe R, Reid CM, Kirpach B, Shah RC, Ives DG, Storey E, Ryan J. Effect of aspirin on all-cause mortality in the healthy elderly. New England Journal of Medicine. 2018; 379(16):1519-28.
- Guo C, Ma W, Drew DA, et al. Aspirin Use and Risk of Colorectal Cancer Among Older Adults. JAMA Oncology. Published online January 21, 2021. doi:10.1001/jamaoncol.2020.7338
- Mora S, Shufelt CL, Manson JE. Whom to Treat for Primary Prevention of Atherosclerotic Cardiovascular Disease: The Aspirin Dilemma. JAMA Intern Med. Published online April 26, 2022. doi:10.1001/jamainternmed.2022.1365