Although the drug rated slightly better than placebo in studies, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin) or diclofenac are better choices for short-term pain relief, the researchers said.

"Regardless of dose, the prescription drug diclofenac is the most effective drug among painkillers in terms of improving pain and function in osteoarthritis," said lead researcher Dr. Sven Trelle. He's co-director of clinical trials at the University of Bern in Switzerland.


However, even diclofenac comes with side effects.

"If you are thinking of using a painkiller for osteoarthritis, you should consider diclofenac," Trelle said, but also keep in mind that like most NSAIDs the drug increases the risk for heart disease and death.

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Tylenol manufacturer McNeil Consumer Healthcare took issue with the new study. "We disagree with the authors' interpretation of this meta-analysis and believe acetaminophen remains an important pain relief option for millions of consumers, particularly those with certain conditions for which NSAIDs may not be appropriate -- including cardiovascular disease, gastrointestinal bleeding, and renal [kidney] disease," the company said in a prepared statement.

"The safety and efficacy profile of acetaminophen is supported by more than 150 studies over the past 50 years," the company added.

The new report was published March 17 in The Lancet.

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Osteoarthritis is the leading cause of pain in older people. It can impair physical activity, and that increases the risk of obesity, heart disease, diabetes and general poor health, the study authors said.

One expert said it's "not surprising" that acetaminophen won't help arthritis pain.

"Osteoarthritis is caused by inflammation of the joints, and acetaminophen is not meant for inflammation," explained Dr. Shaheda Quraishi, a physiatrist at Northwell Health Pain Center in Great Neck, N.Y.

The current research included information from 74 trials published between 1980 and 2015. These trials included more than 58,000 patients. The studies compared how well various doses of acetaminophen and seven different NSAIDs relieved arthritis pain.

The researchers found that acetaminophen was slightly better than an inactive placebo. But they added that taken by itself, acetaminophen has no role in treating osteoarthritis, regardless of dose.

The maximum daily dose of diclofenac -- a prescription pain reliever -- was the most effective treatment for pain and disability, the new study showed. The researchers also found diclofenac was better than the maximum doses of NSAIDs, including ibuprofen, naproxen (Aleve) and celecoxib (Celebrex).

In addition to not helping with pain, one expert pointed out that acetaminophen can also be dangerous.

"Acetaminophen may not be as safe as most people would believe: it is known to be toxic to the liver, and acetaminophen overdose is a leading cause of liver transplantation," said Dr. Nicholas Moore. He's from the department of pharmacology at the University of Bordeaux in France. Moore is also the co-author of an accompanying journal editorial.

"NSAIDs are much more effective painkillers, and avoiding them puts patients at risk of overdosing with acetaminophen," he said.

New painkillers are needed, but "narcotics are not a good choice," Moore added. Prescription narcotic painkillers -- drugs such as Oxycontin, Vicodin and Percocet -- are not as effective as NSAIDs for inflammatory pain, he explained. And the risk of dependency or overdose with narcotics is considerable, he added.

"We should look also at older drugs that may have been discarded, and perhaps work more to understand the mechanism of action of acetaminophen to develop a new, more effective and less toxic drug of the same class, or develop new classes of painkillers," Moore suggested.

More information

For more information on osteoarthritis, visit the Arthritis Foundation.

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