Untreated Respiratory Tract Infections Might Increase Bleeding in Patients Who Use Oral Anticoagulants

Macrolides and fluoroquinolones can increase warfarin's anticoagulant activity, leading to excess bleeding events; macrolides also might promote bleeding in patients taking direct-acting oral anticoagulants (DOACs). However, some evidence suggests that acute infections in patients who are taking anticoagulants are associated with excess bleeding risk, whether or not antibiotics are prescribed.

Using linked outpatient and hospital databases, British investigators identified a cohort of 1200 adult users of warfarin or DOACs who had both a bleeding event and a respiratory tract infection (RTI) for which an antibiotic was not prescribed between 2011 and 2019. Overall, roughly 1 major and 1 nonmajor bleeding event occurred per 1000 patient-days o…