Richelsen RKB, et al. - A historical prospective cohort study of patients treated with intravenous acyclovir in North Denmark Region from 2009 to 2016 was conducted to determine the incidence, predictive factors, and prognosis of acyclovir-induced nephrotoxicity. They analyzed 276 patients treated with intravenous acyclovir of which 29 showed an increase of ≥ 40 μmol/L in plasma creatinine level from baseline. In 14 cases, acyclovir was considered as the main reason for nephrotoxicity, whereas among the 15 remaining patients, a potential competing cause of renal impairment was present. Hypertension was identified to be the only predictive factor associated with nephrotoxicity while having no co-morbidities was identified as protective. Rehydration and dose reduction or discontinuation of the drug led to reversal of nephrotoxicity in all cases. However, cases with acyclovir-induced nephrotoxicity showed significantly higher normalized plasma creatinine upon treatment than cases with a potential competing cause.