Risk factors for renal, vestibular, and auditory toxicity are Frequent or very high doses Very high blood levels of the drug Long duration of therapy (particularly > 3 days) Older age A preexisting renal disorder Coadministration of vancomycin, cyclosporine, amphotericin B, iodinated contrast agents, or other nephrotoxins For auditory toxicity, a genetic predisposition, preexisting hearing problems, and coadministration of loop diuretics High doses given over a long period of time typically cause more concern about renal toxicity, but even low doses given for a short time can worsen renal function.