Reversible renal failure after treatment with omeprazole.

Omeprazole is a proton pump inhibitor widely used in the treatment of gastro-esophageal reflux disease and peptic ulcer disease. In a 73-year-old man we describe renal failure due to acute interstitial nephritis after use of omeprazol during 4 months. Unexpected renal failure without signs of hydronephrosis should always provoke awareness of drug reaction, omeprazole being one of the possible drugs.