The study is yet another blow to patients trying to find ways to treat arthritis pain, after reports that the most advanced drugs, called COX-2 inhibitors, can raise the risk of heart death.

Dr. David Y. Graham of the Baylor College of Medicine in Houston and colleagues studied 21 patients taking a range of drugs called non-steroidal anti-inflammatory drugs, or NSAIDS. They compared them to 20 patients taking acetaminophen, an unrelated painkiller, or nothing.

"Small-bowel injury was seen in 71 percent of NSAID users compared with 10 percent of controls," they wrote in Monday's issue of the journal Clinical Gastroenterology and Hepatology.

"We have always known that NSAIDs can cause potentially deadly stomach complications, but the extent of the impact on the small intestine was largely unknown until now," Graham added.

Arthritis pain is incurable but can be treated with a range of drugs, including NSAIDS such as aspirin, ibuprofen or naproxen; acetaminophen; or the newer drugs called COX-2 inhibitors. NSAIDS work very well but damage the stomach and intestine. They are blamed for 16,500 deaths a year in the United States alone, Graham said.

BENEFIT VS. RISK

"Anybody who takes aspirin or (other) NSAIDS for a year has a 1 to 4 percent risk of serious gastrointestinal complications," Graham said in a telephone interview. "If the drugs didn't have such benefits, we'd have taken them off the market some time ago."

Acetaminophen, sold generically and also under the brand name Tylenol, does not work for many patients, Graham said.

The COX-2s were designed specifically to overcome the deadly side effects of NSAIDS. But a series of studies has linked them to heart disease and one, Merck and Co. Inc.'s Vioxx, was pulled from the market in September.

In December the U.S. Food and Drug Administration issued an advisory telling doctors to limit their prescribing of other COX-2s, including Pfizer's Celebrex and Bextra. And a study published in December indicated that an over-the-counter NSAID called naproxen might also raise the risk of heart attack and stroke.

Graham's team used an endoscope in the form of a swallowed camera in a capsule to examine the intestines of their volunteers. Although people taking NSAIDs frequently suffer stomach pain or anemia, none of the volunteers in this study had any symptoms. "We saw some ulcers and we saw lots of erosions," Graham said.

Some experts have recommended using antacid drugs called proton pump inhibitors (PPI) to reduce the damaging effects of stomach acid in NSAID patients. But PPIs do not affect the small intestine, Graham said.

Instead, he said, an older drug called misoprostol can help protect the stomach lining. "It is the only drug approved to reduce the rate of bleeding," Graham said.

A U.S. government study published last month found that acupuncture can help to further relieve arthritis pain in the knee in patients getting more standard treatment.

The American Gastroenterological Association estimates that more than 30 million Americans take over-the-counter or prescription drugs for headaches and arthritis.