Omeprazole (Prilosec) is a proton pump inhibitor (PPI) that is used to reduce the amount of acid in your stomach and it can be bad for your kidneys. It can cause acute kidney injury and may also worsen the progression of chronic kidney disease (CKD).

Omeprazole can cause acute kidney injury

One of the reported serious side effects of omeprazole is a type of kidney problem called acute tubulointerstitial nephritis. This is a type of acute kidney injury, but it can lead to chronic kidney disease.

Acute tubulointerstitial nephritis occurs when inflammatory cells infiltrate the part of the kidney known as the interstitium. It is an immune-mediated process. It is recommended that you call your doctor right away if you have blood in your urine or you have a decrease in the amount you urinate while taking omeprazole.

Omeprazole may worsen the progression of chronic kidney disease

The use of PPIs, in particular omeprazole, has also been associated with the development of CKD. It is thought that this may be due to omeprazole causing oxidative stress and renal tubular cell death.

In one study following 199 patients with CKD for a year, 70.6 percent of patients using omeprazole had disease progression compared with only 10.5 percent of patients who did not take omeprazole.

An analysis of Food and Drug Administration (FDA) post marketing surveillance data has also shown that people taking PPIs are 28.4 (95% CI 12.7-63.5) times more likely to report CKD and 35.5 (95% CI 5.0-250) times more likely to report end-stage renal disease (ESRD) than people taking histamine-2 receptor antagonists (H2RAs). H2RAs, or H2 blockers, are another class of drug used to reduce the amount of acid produced in the stomach, but they are not considered to work as well as PPIs. Examples of H2 blockers include nizatidine (Axid), famotidine(Pepcid, Zantac 360) and cimetidine (Tagamet).