MONDAY, March 2, 2015 (HealthDay News) -- Acetaminophen may not be as safe as previously thought, with larger doses and long-term use linked to increased risk of health problems, a new report contends.

Best known in the United States under the brand name Tylenol, acetaminophen is the most widely used painkiller in the world, the study authors said in background notes.

It is the World Health Organization's front-line treatment for pain, and is considered safer than nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen, the researchers said.

But a small group of studies has raised questions about acetaminophen's safety if used for a long time and at high doses to treat chronic pain, said lead author Dr. Philip Conaghan, a professor with the Leeds Institute of Rheumatic and Musculoskeletal Medicine in England.

Heavy use of acetaminophen is associated with kidney disease and bleeding in the digestive tract, the paper reports. The medication also has been linked to increased risk of heart attack, stroke and high blood pressure, the study authors noted.

One cited study even showed that overuse of acetaminophen can increase a person's risk of early death as much as 60 percent, the study authors found.

"Bigger doses seem to be more associated with those side effects," Conaghan said. "It's yet another reason for us to be careful of what drugs people take long-term, because they all have side effects."

The study authors are calling for a new systematic review of acetaminophen's effectiveness and safety, saying that the medication's true risks are "higher than that currently perceived in the clinical community." The cited side effects appear similar to those of NSAIDs.

Acetaminophen still seems safe when taken occasionally, or when taken at moderate doses for treatment of long-term chronic pain, said Dr. Robert Wergin, president of the American Academy of Family Physicians.

"It still may be the right drug, if used at the proper dose," Wergin said. "I feel like this study probably wouldn't change my message to my patients," which includes telling them to avoid extra-strength versions of acetaminophen and stick to the directions for use.