Nonsteroidal anti-inflammatory drugs (NSAIDs) are likely to be used concomitantly with acyclovir or valacyclovir in clinical practice, but the study on the safety of such combinations was seldom reported. The objective of the study was to investigate reports of acute kidney injury (AKI) events associated with the concomitant use of oral acyclovir or valacyclovir with an NSAID by using the United States Food and Drug Administration (FDA) Adverse Event Reporting System (AERS) database between January 2004 and June 2012. The frequency of AKI events in patients while simultaneously taking either acyclovir or valacyclovir and an NSAID was compared using the Chi-square test. The effect of concomitant use of acyclovir or valacyclovir and individual NSAIDs on AKI was analyzed by the reporting odds ratio (ROR). The results showed that AKI was reported as the adverse event in 8.6% of the 10923 patients taking valacyclovir compared with 8.7% of the 2556 patients taking acyclovir (p=NS). However, AKI was significantly more frequently reported in patients simultaneously taking valacyclovir and an NSAID (19.4%) than in patients simultaneously taking acyclovir and an NSAID (10.5%) (p<0.01). The results also suggested that increased risk of AKI was likely associated with the concomitant use of valacyclovir and some NSAIDs such as loxoprofen, diclofenac, etodolac, ketorolac, piroxicam or lornoxicam. The case series from the AERS indicated that compared with acyclovir, valacyclovir is more likely to be affected by NSAIDs, and the concomitant use of valacyclovir with some NSAIDs might be associated with increased risk of AKI. The drug interactions with this specific combination of medications are worth exploring further.