Long-term, habitual use of the painkiller acetaminophen - known as paracetamol in many parts of the world - may cause a decline in kidney function in some people, according to a study of middle-aged women published on Monday.

Overall, one in 10 of the 1,700 women studied over 11 years experienced a 30 percent decline in their kidney’s filtration function.

Acetaminophen, which is sold under the brand name Tylenol by a subsidiary of Johnson & Johnson and is also marketed generically, was alone among commonly used painkillers to show an association with kidney impairment.

“Our findings should not prompt people to discontinue using acetaminophen,” said study author Gary Curhan of Brigham and Women’s Hospital in Boston. 

“Instead, this study suggests a need for the medical community to consider alternative pain therapies that may help patients avoid long-term dependence on these drugs until we clearly understand the potential side effects.

“The good news is that, based on this research, it appears that for the vast majority of women, most pain relievers are safe for the kidney,” Curhan said.

In the study, which was published in the Archives of Internal Medicine, women who had taken between 1,500 and 9,000 tablets over their lifetimes raised their risk of kidney impairment by 64 percent.

For those who took more than 9,000 tablets, the risk more than doubled.

There was no association in this study between kidney impairment and aspirin or other anti-inflammatory drugs known collectively as non-steroidal anti-inflammatory drugs (NSAIDs), but some previous research has shown a connection.

“Pain relievers are used commonly, especially among women,” Curhan said. “As a growing number of patients take painkillers on a regular basis to alleviate chronic pain or to prevent heart disease and stroke, it is important for clinicians to fully appreciate that these medications may also have adverse effects on an individual’s long-term health.”

SOURCE: Archives of Internal Medicine, July 26, 2004.