BAKERSFIELD, Calif. -- Last year, Americans received more than 100 million prescriptions for acid reflux drugs such as Prevacid or Prilosec -- medications in a class called proton pump inhibitors.

These popular drugs outsold every other class of medication except cholesterol drugs and antipsychotics.

But new evidence has found the acid reflux pills may be creating dependency in patients who use them.

Researchers in Denmark tested Prilosec in healthy volunteers who had never experienced acid reflux problems. Results revealed that 40 percent of participants started experiencing symptoms such as heartburn, chest pain, and acid reflux after they stopped the drug.

The medications work by blocking acid pumps in stomach cells, but researchers said that ceasing the drugs may trigger a rebound effect that creates more acid.

They suggested this is why one third of patients continue to fill their prescriptions even after they have theoretically completed treatment.

While the drugs overall have an excellent safety record, studies have linked long-term use of proton pump inhibitors to an increased risk for fractures.