Just about everyone has experienced heartburn. It’s that intense burning feeling in your chest from acid refluxing upward from the stomach into the esophagus, the tube that carries food down the digestive tract.

Even though it is quite common, doctors aren’t really sure what causes it, said Daniel DeMarco M.D., medical director of endoscopy at Baylor University Medical Center in Dallas, a board certified gastroenterologist and founder of the Baylor Heartburn Center. “The current thinking is that the acid is refluxed upward because of temporary, inappropriate relaxations of the lower esophageal sphincter, the valve between the stomach and the esophagus.”

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Peristalsis, a rhythmic contraction of muscles, propels food down into the stomach. The valve opens to let the food in and then closes. However, in certain individuals the valve doesn’t function as well as it should. It opens up inappropriately, relaxes, opens again and allows acid to reflux upward. This can happen when you bend over, lie down, or eat a big meal.

DeMarco said that, despite all of the hype, there is no real evidence that weight affects heartburn. There are studies that show that after people have lost weight their acid reflux didn’t change. But there also are studies that show it did, DeMarco said. He added that extra weight does cause increased pressure on the chest, but even normal weight people have increased pressure on their chest at times.

There are several over-the-counter remedies that can successfully treat ordinary heartburn. DeMarco recommends following a three-step method to find the product that is right for you:

— Simple antacids – These neutralize the acids right away. Liquid antacids are especially effective. “That’s why,” Dr. DeMarco said, “my doctor says Mylanta.”

— H2 Blockers – This is a class of drugs, also known as H2 receptor antagonists, that temporarily stop the production of acid. There are three receptors on the parietal cells in the stomach lining that tell the cells to make acid. The histamine receptor is one of them. H2 Blockers block the signals from the histamine receptor that stimulate acid production. The most effective remedies in this class are Tagamet, Zantac, and Pepcid.

Proton Pump Inhibitors – This is a class of drugs designed to provide the most powerful and long-lasting reduction of acid. Proton pump inhibitors act by permanently and irreversably blocking the proton pump inside the stomach cells, which is the mechanism that actually produces the acid. Prilosec is a popular over-the-counter proton pump inhibitor.

DeMarco said that taking away acid production permanently may have some long-term side effects, but doctors haven’t really seen any yet. “There was a single study that showed that stopping acid production caused problems with calcium absorption, and increased incidences of osteoporosis and pneumonia,” he said. “However, the incidences were rare.”

Typically, the nocturnal symptoms, which disturb normal sleep habits, are the most problematic for the majority of heartburn sufferers. But there are times when heartburn may be symptomatic of something more serious.

“It should raise a red flag if you are a middle-aged person who never had heartburn and suddenly you have it and you don’t get relief,” De Marco added. “That’s when it’s time to see your doctor to be sure that it is heartburn and not a heart attack. Also, if you have trouble swallowing or you’re losing weight in addition to the heartburn, these could be signs of esophageal cancer.”