Nearly 98% percent of people prescribed direct-acting oral anticoagulants such as apixaban also used over-the-counter products. Of those, 33% took at least one such product that, in combination with the anticoagulants, could cause dangerous internal bleeding. People taking these medications largely lacked knowledge of some potentially serious interactions.


Direct-acting oral anticoagulants are the drug of choice for stroke prevention in patients with atrial fibrillation, which occurs most frequently in older patients. Apixaban is one of the most frequently prescribed. However, most people prescribed apixaban or other direct-acting oral anticoagulants are not followed in specialized anticoagulation clinics or monthly by health care professionals. As a result, these people may not be aware of potential drug interactions.


From April to October 2018, the researchers surveyed 791 English- and Spanish-speaking patients who had been prescribed apixaban. Subjects were asked about their knowledge of potential interactions between the drug and over-the-counter supplements. They were asked about how often they took aspirin, ibuprofen/naproxen, and acetaminophen, and 13 common dietary supplements, including Chinese herbs, various fish oils, ginger and herbal teas, while also taking apixaban.

Limitations to the study included a low response rate (33%), self-reported data, which can be unreliable due to faulty memories, and the researchers’ focus on a limited number of dietary supplements.


Because such a large number of people lack knowledge of drug interactions, there is a need to educate patients and health care providers about the dangers that the combinations may pose. In addition, data are needed on outcomes in people who combine apixaban and over-the-counter products.


The study’s authors are Dr. Derjung Tarn of UCLA; Maureen Barrientos, Dr. Margaret Fang, and Dr. Janice Schwartz of UC San Francisco; and Angel Wang and Abhijit Ramaprasad of the University of Chicago.


The study was published in the Journal of the American Geriatrics Society.


The research was funded by the National Center for Advancing Translational Sciences; the National Institutes of Health, through the UCLA and UCSF Clinical and Translational Science Institutes; the National Heart, Lung, and Blood Institute; BMS/Pfizer Alliance American Thrombosis Investigator Initiated Research Program; and the University of Chicago Jeff Metcalf Internship Program.


Tarn and Schwartz received funding from the BMS/Pfizer Alliance ARISTA-USA for the study. Schwartz is on advisory boards for Bristol Myers Squibb and Pfizer.