Patients who suffer from heartburn are not at increased risk for heart problems as a result of taking Prilosec or Nexium, according to a review released Monday by the Food and Drug Administration.

The FDA and its Canadian counterpart began reviewing the drugs, used by tens of millions of people, back in May. The drug's manufacturer, AstraZeneca PLC, provided them with an early analysis of two small studies that suggested the possibility of a risk.

The FDA said its review of that study as well as 14 others indicated no increased risk for patients, although the agency said the studies were not specifically conducted to assess the risk of heart problems and patient follow-up was incomplete.

"FDA recommends that health care providers continue to prescribe, and patients continue to use these products as prescribed," the agency said.

Prilosec and Nexium are members of a class of drugs known as proton pump inhibitors As prescription products, they are used to treat the symptoms of gastroesophageal reflux disease, or GERD, and other conditions caused by excess stomach acid.

The drugs work to decrease the amount of acid produced in the stomach and help heal erosions in the lining of the esophagus known as erosive esophagitis. They are also indicated for use with an antibiotic to treat gastric ulcers. Prilosec is also available as an over-the-counter medication to treat frequent heartburn.

Nexium is the world's No. 2 selling drug, with 2006 sales of $6.7 billion, according to health care research firm IMS Health.