Nephritis is an important ‘renal’ cause of acute kidney injury, though less common than, acute tubular necrosis and acute glomerulonephritis. Interstitial inflammation is also seen in glomerular diseases, but is not considered as AIN, possibly because of different pathophysiology. Two-thirds of cases of AIN are due to drugs like NSAIDs and antimicrobials. The presentation of AIN is with non-specific symptoms and signs, with <10% patients having systemic features of immune reaction like fever, rashes, arthralgias, and eosinophilia. Most of the cases of AIN are diagnosed clinically. Biopsy, when available, shows interstitial oedema and infiltrates of lymphocytes, macrophages, eosinophils, plasma cells, and neutrophils. The glomeruli are typically normal