On Aug. 24, 2020, the combination of hydroxychloroquine and azithromycin has been linked to significant cardiovascular risks, including mortality, in the largest safety study ever performed comparing hydroxychloroquine treatment to hydroxychloroquine and azithromycin treatment for rheumatoid arthritis patients.

Hydroxychloroquine is commonly used to treat rheumatoid arthritis, while azithromycin is a frequently-prescribed antibiotic to treat infections such as pneumonia, chest and sinus infections, etc. This network study, led by the Observational Health Data Sciences and Informatics (OHDSI) community, was published in Lancet Rheumatology.