DefinitionInterstitial nephritis is a kidney disorder in which the spaces between the kidney tubules become swollen (inflamed). The inflammation can affect the kidneys' function, including their ability to filter waste.Alternative NamesTubulointerstitial nephritis; Nephritis - interstitial; Acute interstitial (allergic) nephritisCauses, incidence, and risk factorsInterstitial nephritis may be temporary (acute) or it may be long-lasting ( chronic) and get worse over time.The following can cause interstitial nephritis:Allergic reaction to a drug (acute interstitial allergic nephritis)Analgesic nephropathyLong-term use of medications such as acetaminophen (Tylenol), aspirin, and nonsteroidal anti-inflammatory drugs (NSAIDS). This is called analgesic nephropathySide effect of certain antibioti