Daily low-dose aspirin has its benefits — and risks. Here's how to figure out if you should take it or skip it.

For years, doctors recommended that older adults at a higher risk for heart attack or stroke take a low-dose aspirin once a day to lower their risk. Aspirin helps prevent blood clots from forming, which is the leading cause of heart attack and stroke, but the drug also carries a risk of bleeding. That risk can outweigh aspirin’s benefits in some cases, which is why recommendations have shifted in recent years.

Research-backed guidance from the American Heart Association (AHA) published in 2019 advised against routinely taking baby aspirin to lower the risk of cardiovascular disease. That was followed by a 2022 recommendation from the U.S. Preventive Services Task Force (USPSTF) stressing that people ages 60 or older should not take a daily baby aspirin for heart health. However, the task force added that there is a “small net benefit” in taking aspirin to lower cardiovascular disease risk in people between the ages of 40 and 59 with a higher risk of developing heart issues within the next decade, leaving plenty of people confused.

Meanwhile, research shows that millions of people still take baby aspirin, despite not having risks for heart disease.

So what do you need to know about the potential benefits and risks of aspirin? And who should take or avoid it? Doctors break it down.

Does aspirin help prevent colon cancer?

Several studies have found that taking aspirin may lower the risk of developing colon cancer and polyps, per the American Cancer Society (ACS). Aspirin may boost the body’s immune response against cancer cells. However, research has been mixed on whether regularly taking aspirin helps lower the odds that someone who has been diagnosed with colorectal cancer will die of the disease.

More recently, a study of more than 100,000 people published in early August found that those who led less healthy lifestyles — they smoked, drank more alcohol and didn’t have much physical activity, to name a few things — had a lower risk of dying from colorectal cancer when they took aspirin compared to people who led healthier lifestyles. While people with healthier lifestyles had a lower baseline risk of developing colorectal cancer, taking aspirin had a greater impact on those who had unhealthy lifestyles.

Does aspirin protect heart health?

Research around the use of aspirin for cardiovascular health is also mixed. Data from three large clinical trials published in 2018 found that, while there was a small benefit of taking daily aspirin for heart health, there was also an increased risk of developing gastrointestinal and brain bleeding. This information was studied by the USPSTF when it made its decision to recommend against taking a daily aspirin, along with data from 14 other randomized controlled trials. Based on all of that, the USPSTF concluded that taking a daily aspirin can increase the risk of having major gastrointestinal bleeding by up to 60% and brain bleeding up to 30%.

A 2021 study also analyzed data from nearly 31,000 people at risk for developing heart failure and found that those who took aspirin had a 26% higher risk of heart failure than those who didn’t take the drug.

An analysis of three clinical trials published in February found that people who took aspirin for heart disease or stroke and then stopped taking the medication had a 28% higher risk of the serious health events. As a result, the researchers concluded that people who are already taking a low-dose aspirin keep on taking it unless they have significant risk factors for aspirin-related bleeding.

But because aspirin is a blood thinner, doctors say it still has valid use under certain circumstances.

Who should — and shouldn’t — take daily aspirin?

Doctors still recommend taking aspirin, although it tends to be in much more specific instances than in the past. Dr. Janet O'Mahony, a Baltimore-area internal medicine doctor at Mercy Medical Center, tells Yahoo Life: “Where aspirin is used more commonly these days is as an antiplatelet agent,” or blood thinner. Because of its blood-thinning ability, she says, “we use aspirin to treat a person when they are in the midst of a heart attack or stroke.”

Aspirin may also be used to lower the risk of a heart attack or stroke in people who have already had one, O’Mahony says. But that path is not without risk. “This medication can increase the risk of bleeding from the stomach and bleeding in the brain,” she notes. But for those at a particularly high risk, “the benefit of preventing heart attack and stroke outweighs the risks."

Dr. Wael Harb, a hematologist and medical oncologist at MemorialCare Cancer Institute at Orange Coast and Saddleback Medical Centers in Orange County, Calif., tells Yahoo Life that “certain individuals with a history of cardiovascular disease, whether high risk for heart attack or stroke, should be taking aspirin” under the guidance of their physician. “It may also be beneficial in people with a high risk of colorectal cancer,” he adds.

Harb says that recommendations on this need to be more specific — and communicated better to the public. “We’re moving from generalized recommendations about aspirin to more of a personalized approach,” he says. “We need to do a better job pinpointing the subset of patients who would really benefit, and when the benefits outweigh the risks.” The most recent colorectal cancer study came to a similar conclusion, noting that it may be better to target aspirin use in some high-risk patients for colorectal cancer vs. making a blanket recommendation.

But there are other factors to consider with aspirin use, including additional underlying health complications you may have or medications you take. “There are certain medications that interact with aspirin, such as digoxin and warfarin,” Jamie Alan, an associate professor of pharmacology and toxicology at Michigan State University, tells Yahoo Life. “There are also conditions such as stomach ulcers where aspirin is not recommended.”

The bottom line

Doctors stress the importance of talking to your health care provider before putting yourself on a daily dose of baby aspirin, which is typically 81 milligrams. “But sometimes in people with blood disorders, we would recommend 325 milligrams,” he says. “The dose is really dependent on the patient.”

Until more research is done, the jury is still out on whether the general population would benefit from taking daily aspirin to prevent colon cancer. For heart health, in general, if you have a low risk of heart attack, the protective benefits of daily aspirin don't outweigh the bleeding risks. But if you have a higher risk of a heart attack — particularly if you're between the ages of 40 and 59 with a higher likelihood of having a first-time heart attack or stroke within the next decade — then the benefits may be greater than the risks of bleeding.

Harb says that a doctor can help assess your personal needs. “The risks and benefits need to be weighed carefully,” he says.