Prospective cohort study of ototoxicity in persons with cystic fibrosis following a single course of intravenous tobramycin

•A single course of IV tobramycin results in a statistically significant loss of hearing threshold in adults with CF.•Because of the cumulative effect of hearing loss, 46 – 67% of CF patients already demonstrate hearing loss in the EHF by average age 29 years old.•The ASHA shift measurement provides a good screening mechanism for an individual patient, but may not be an ideal metric for comparing ototoxic hearing loss across groups of patients.•Ototherapeutic treatments would be useful for protecting the hearing of patients with cystic fibrosis treated with aminoglycosides.