Nexium is the brand name of the generic drug esomeprazole, and belongs in a class of medications known as proton pump inhibitors. It works by turning off, at the cellular level, the part of the stomach, the proton pump, that produces stomach acid, according to Medline Plus. It is prescribed by doctors to treat frequent heartburn, gastroesophageal reflux disease and stomach ulcers. As of 2010, the generic form of Nexium is not available for purchase in the United States, and patients concerned about Nexium's high cost may want to consider other generic proton pump inhibitors on the market.

Omeprazole is the generic name of the brand name drug Prilosec. Like Nexium, omeprazole works by turning off the acid-producing mechanism in the stomach, or the proton pump, according to Medline Plus. Omeprazole is available for purchase over-the-counter. ConsumerReports.org lists the average monthly price--as of 2010--of taking omeprazole at $19, compared to $240 for Nexium. Patients should consult with their doctors before switching from a prescription medication to an over-the-counter medication.

Pantoprazole is the generic name of the brand name drug Protonix. Pantoprazole is another proton pump inhibitor, but unlike omeprazole, pantoprazole requires a prescription from a doctor. ConsumerReports.org reports that generic pantoprazole costs about $140 a month.

While not available in generic form, Prevacid 24 is another proton pump inhibitor that is available for purchase over-the-counter. According to ConsumerReports.org, the average monthly cost of taking Prevacid 24 is $23. Patients looking for an alternative to Nexium may want to ask their doctors if Prevacid 24 is right for them.