Hi, Nexium (esomeprazole) is a proton pump inhibitor used to treat acid peptic disorders. All proton pump inhibitors are associated with a renal condition called interstitial nephritis. i would like you to confirm with your nephrologist whether you are suffering from this particular condition. If not, you need to undergo investigations to find out the cause. If you are suffering from interstitial nephritis, you might need to change over to other class of drugs called antihistamines like ranitidine that helps in controlling the symptoms of heartburn. Apart from medications, lifestyle modifications like avoiding spicy food, sleeping on the left side helps in reducing the symptoms of heartburn. I hope the above information helps you. Thanks for writing into healthcaremagic. Have a nice day.