The maximum daily dose of Extra Strength Tylenol brand acetaminophen will soon be six, not eight, pills a day in the U.S. But the limits aren't changing in Canada.

Labels on the U.S. bottles will now list the maximum daily dose as 3,000 milligrams, or six pills a day, down from 4,000 milligrams, or eight pills a day.

Similar changes are planned for other Tylenol products in 2012, J&J said.

Following a string of accidental overdoses, advisors to the Food and Drug Administration called for restrictions on acetaminophen two years ago.

The change does not affect Canada. Shelley Kohut, director of communications and public relations at Johnson & Johnson Inc., told The Canadian Press that the labelling instructions will remain the same in Canada.

The maximum daily dose for Extra Strength Tylenol in Canada is eight pills or 4,000 milligrams per day.

Kohut noted that Health Canada reviewed and approved the label standard for acetaminophen products in 2009.

Acetaminophen is the active ingredient in Tylenol and numerous other prescription and nonprescription pain relievers, including Percocet, Vicodin, NyQuil and some Sudafed.

McNeil Consumer Healthcare, the division of Johnson & Johnson that manages Tylenol, insists Tylenol is safe when taken as directed on the package.

"Acetaminophen is safe when used as directed. But, when too much is taken (overdose), it can cause liver damage," said Dr. Edwin Kuffner, vice president of OTC (over-the-counter) Medical Affairs and Clinical Research at McNeil.

He noted that some people accidentally exceed the recommended dose when taking multiple products at the same time that all contain acetaminophen.

"McNeil is revising its labels for products containing acetaminophen in an attempt to decrease the likelihood of accidental overdosing in those instances," he said.