Television ads from law firms hunting for plaintiffs against drug makers appear to scare patients off medicines they need. A study of blood thinners found that these drug injury ads reduced prescription fills for the targeted drugs and raised hospitalizations for the conditions those drugs prevent.
The paper is by Sylvia Hristakeva of the SC Johnson College of Business at Cornell University. It was published online in Management Science on October 28, 2025.
Ads aimed at plaintiffs, seen by patients
Drug injury ads, also called bad-drug or mass tort ads, invite people harmed by a medication to join a lawsuit. They also reach millions of viewers who are taking the drug without problems, and doctors have worried that the ads lead patients to stop treatment.
Hristakeva studied newer oral anticoagulants, the blood thinners Xarelto, Pradaxa and Eliquis, used mainly by older adults to prevent strokes. Clinical trials had found these drugs at least as safe as the older drug Warfarin, but lawyers ran large ad campaigns alleging a failure to warn about bleeding risks.
She combined data on local and national mass tort TV ads from X Ante with Medicare Part D prescription records and Medicare inpatient hospital data from 2015 to 2019. To avoid confusing ad targeting with local demand, she compared neighbouring counties on opposite sides of television market borders, which received different amounts of advertising.
Fewer fills, more strokes and clots
The published study finds that the ads decreased filled prescriptions for the targeted drugs and caused a corresponding increase in hospitalizations for conditions treated with anticoagulants, such as stroke, pulmonary embolism and atrial fibrillation.
In a working-paper version dated April 28, 2025, Hristakeva estimates that an increase in ad spending of 19 cents per person cut fills of the newer drugs by 2.6%. In counties with larger shares of older residents, the same increase raised hospitalizations for relevant diagnoses by 5.4%, or roughly 3,200 extra inpatient visits a year.
Placebo checks found no link between the ads and prescriptions for unrelated drugs, hospital visits for hip and femur procedures, or hospitalizations for bleeding, the side effect the ads warned about.
A case for balanced information
Hristakeva notes she could not observe the content of individual ads, so she cannot say which messages did the most harm. Her data are annual and do not separate new prescriptions from refills.
She points to the Federal Trade Commission’s September 2019 warning letters to seven law firms over misleading drug injury ads, and argues for policies that give patients accurate, balanced information. Similar ads are already targeting GLP-1 drugs such as Ozempic and Wegovy.
Study Details:
- Title: Bad-Drug Ads or Killer Ads: The Effects of Drug Injury Advertising on Public Health
- Authors: Sylvia Hristakeva
- Journal: Management Science
- Publication Date: October 28, 2025
- DOI: 10.1287/mnsc.2023.04294