Why You Shouldn’t Use Aspirin While on a Blood Thinner

According to recent research, stopping the use of aspirin while taking a blood thinner reduces the risk of bleeding.

Recent research indicates that you might not need to take a second blood thinner if you already take one.

In fact, a Michigan Medicine study reveals that patients’ risk of bleeding complications significantly decreases when they stop taking aspirin while using a commonly prescribed blood thinner.

Over 6,700 patients who were being treated for blood clots (venous thromboembolism) and atrial fibrillation (abnormal heart rhythm that can lead to stroke) at anticoagulation clinics in Michigan were studied by researchers. Despite not having a history of heart disease, patients were given aspirin in addition to the common blood thinner warfarin as part of their treatment.

“We know that aspirin is not a panacea drug as it was once thought to be and can in fact lead to more bleeding events in some of these patients, so we worked with the clinics to reduce aspirin use among patients for whom it might not be necessary,” said Geoffrey Barnes, M.D., senior author of the study and a cardiologist at the University of Michigan Health Frankel Cardiovascular Center.

Aspirin use among patients fell by 46.6% during the study intervention. The risk of a bleeding complication decreased by 32.3% when aspirin was used less frequently, which equates to one major bleeding event being averted for every 1,000 patients who stop taking aspirin. The study was recently published in the journal JAMA Network Open.

“When we started this study, there was already an effort by doctors to reduce aspirin use, and our findings show that accelerating that reduction prevents serious bleeding complications which, in turn, can be lifesaving for patients,” said Barnes, who is also an associate professor of internal medicine at U-M Medical School. “It’s really important for physicians and health systems to be more cognizant about when patients on a blood thinner should and should not be using aspirin.”

Risks of Combining Aspirin with Other Blood Thinners

This de-escalation of aspirin use is based on several studies that found concerning links between the concurrent use of aspirin and different blood thinners.

One study reported that patients taking warfarin and aspirin for atrial fibrillation and VTE experienced more major bleeding events and had more ER visits for bleeding than those taking warfarin alone. Similar results occurred for patients taking aspirin and direct oral anticoagulants – who were found more likely to have a bleeding event but not less likely to have a blood clot.

“While aspirin is an incredibly important medicine, it has a less widely used role than it did a decade ago,” Barnes said. “But with each study, we are seeing that there are far fewer cases in which patients who are already on an anticoagulant are seeing benefit by adding aspirin on top of that treatment. The blood thinner they are taking is already providing some protection from clots forming.”

When Aspirin Remains Essential

For some people, aspirin can be lifesaving. Many patients who have a history of ischemic stroke, heart attack, or a stent placed in the heart to improve blood flow – as well as those with a history of cardiovascular disease – benefit from the medication.

The challenge comes when some people take aspirin without a history of cardiovascular disease and are also prescribed an anticoagulant, said first author Jordan Schaefer, M.D., a hematologist at U-M Health and clinical associate professor of internal medicine at U-M Medical School.

“Many of these people were likely taking aspirin for primary prevention of heart attack or stroke, which we now know is less effective than once believed, and no one took them off of it when they started warfarin,” Schaefer said. “These findings show how important it is to only take aspirin under the direction of your doctor and not to start taking over-the-counter medicines like aspirin until you review with your care team if the expected benefit outweighs the risk.”

Reference: “Assessment of an Intervention to Reduce Aspirin Prescribing for Patients Receiving Warfarin for Anticoagulation” by Jordan K. Schaefer, MD, Josh Errickson, Ph.D., Xiaokui Gu, MD, MA, Tina Alexandris-Souphis, RN, Mona A. Ali, PharmD, Brian Haymart, RN, MS, Scott Kaatz, DO, MSc, Eva Kline-Rogers, MS, RN, NP, Jay H. Kozlowski, MD, Gregory D. Krol, MD, Vinay Shah, MD, Suman L. Sood, MD, MSCE, James B. Froehlich, MD, MPH and Geoffrey D. Barnes, MD, MS, 19 September 2022, JAMA Network Open.
DOI: 10.1001/jamanetworkopen.2022.31973

The study was funded by the Blue Cross Blue Shield of Michigan. 

Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.