In a retrospective cohort study of patients enrolled in the UK Clinical Practice Research Datalink during 2000-2013, we evaluated long-term risks of death, stroke, and acute myocardial infarction (AMI) in adults prescribed clarithromycin. Patients were outpatients aged 40-85 years, who were prescribed clarithromycin (n = 287,748), doxycycline (n = 267,729), or erythromycin (n = 442,999), or Helicobacter pylori eradication therapy with a proton pump inhibitor, amoxicillin, and either clarithromycin (n = 27,639) or metronidazole (n = 14,863). We analyzed time to death, stroke, or AMI with Cox proportional hazards regression. The long-term hazard ratio for death following 1 clarithromycin versus 1 doxycycline prescription was 1.29 (95% confidence interval (CI): 1.21, 1.25), increasing to 1.62 (95% CI: 1.43, 1.84) for ≥5 prescriptions of clarithromycin versus ≥5 prescriptions for doxycycline. Erythromycin showed smaller risks in comparison with doxycycline. Stroke and AMI incidences were also increased after clarithromycin but with smaller hazard ratios than for mortality. For H. pylori eradication, the hazard ratio for mortality following clarithromycin versus metronidazole regimens was 1.09 (95% CI: 1.00, 1.18) overall, and it was higher (hazard ratio = 1.65, 95% CI: 0.88, 3.08) following ≥2 prescriptions in subjects not on statins at baseline. Outpatient clarithromycin use was associated with long-term mortality increases, with evidence for a similar, smaller increase with erythromycin.