US regulators reviewed the drugs after two clinical trials suggested that they increased the risk of heart attacks and cardiac death.
Nexium and Prilosec are proton pump inhibitors used in the treatment of acid-reflux disease, ulcers and other conditions.
“Based on everything we know now, FDA’s preliminary conclusion is that the observed difference in risk of heart attacks and other heart related problems seen in early analyses of the two small long-term studies is not a true effect,” the regulator said in a statement.