Affairs of the heartburn: drugs for stomach acid may hike pneumonia risk.

In a study sure to cause indigestion among those who can least abide it, Dutch researchers have found that acid-blocking drugs might boost a person's chance of getting pneumonia. For millions of people who have come to rely on the popular drugs, the news is a bitter pill to swallow.

Acid blockers come in two forms. Socalled [histamine.sub.2]-receptor antagonists include ranitidine (Zantac), cimetidine (Tagamet), and famotidine (Pepcid AC). More-potent drugs called proton-pump inhibitors include omeprazole (Prilosec), pantoprazole (Protonix), lansoprazole (Prevacid), and rabeprozole (Aciphex).

The researchers consulted medical records logged between 1995 and 2002 for more than 360,000 people and found that those using acid blockers experienced pneumonia at the rate of about 0.024 case per person each year. That made them 4.5 times as likely to develop pneumonia as were people of a similar age and the same gender who never used the drugs.

Next, the scientists assessed pneumonia rates among 475 people who used acid blockers during the study years and matched each of these individuals with 10 people of the same age, gender, and general health characteristics who had stopped taking the drugs at some earlier date.

From these records, the researchers calculated that a person taking a proton-pump inhibitor has nearly twice the risk of getting pneumonia as does someone who has stopped taking the drug. A [histamine.sub.2]-receptor antagonist boosted the risk of pneumonia by about two-thirds over the risk in past users, the researchers report in the Oct. 27 Journal of the American Medical Association. The researchers didn't analyze the use of chewable antacids.

The acid in a person's stomach not only aids digestion but also kills pathogens coming from the mouth via the esophagus. "There's lots of data showing that if you take away acid, it increases bacteria in the stomach," says James C. Gregor of the University of Western Ontario in London, Ontario. Some of these microbes might move up the esophagus and then down into the lungs, causing pneumonia, he says.

The new study indicates that there's only a small chance of contracting pneumonia that way, even among people taking acid-blocking drugs, says coauthor Robert J.F. Laheij, an epidemiologist at the University Medical Center St. Radboud in Nijmegen, the Netherlands. It's unclear whether the added risk outweighs the benefits that acid blockers provide, he says.

Acid suppression does more than relieve indigestion and heartburn. It limits damage to the esophagus, which can undergo scarring and even develop cancer after pro longed acid exposure.

"These drugs are an incredible advance in terms of quality of life and healing disease,' says Gregor.

Nevertheless, the data suggest that the heightened pneumonia risk could be particularly worrisome for immune-suppressed individuals, the elderly, or those with chronic lung problems, Laheij says.

"This makes us think twice about leaving people on these drugs forever," Gregor says.