Acute interstitial nephritis (AIN) may be a contributory factor in up to 35% of cases of acute kidney injury. The typical histological lesion is infiltration of the interstitial renal tissue by inflammatory cells. AIN can complicate a variety of diseases, including autoimmune conditions (Sjögren’s syndrome, inflammatory bowel diseases, primary biliary cholangitis and sarcoidosis), infections, oxalosis, mushroom intoxication and exposure to certain drugs (antibiotics, non-steroidal anti-inflammatory drugs and proton pump inhibitors). AIN often progresses to interstitial fibrosis necessitating prompt identification and appropriate treatment. Steroids are the mainstay of therapy in AIN associated with autoimmune diseases, while their role in drug-induced AIN is less clear cut. Read more about the aetiology and treatment of AIN in the latest NDT Digest article.