Bottles of Tylenol sold in the U.S. will soon bear red warnings alerting users to the potentially fatal risks of taking too much of the popular pain reliever.

The unusual step, disclosed by the company that makes Tylenol, comes amid a growing number of lawsuits and pressure from the federal government that could have widespread ramifications for a medicine taken by millions of people every day.

Johnson & Johnson says its U.S. bottles of Extra Strength Tylenol will bear a new warning label on the cap to alert users to potentially fatal risks of taking too much of the pain reliever. Johnson & Johnson says its U.S. bottles of Extra Strength Tylenol will bear a new warning label on the cap to alert users to potentially fatal risks of taking too much of the pain reliever. (Johnson & Johnson/Associated Press)

Johnson & Johnson says the warning will appear on the cap of new bottles of Extra Strength Tylenol sold in the U.S. starting in October and on most other Tylenol bottles in coming months. The warning will make it explicitly clear that the over-the-counter drug contains acetaminophen, a pain-relieving ingredient that's the leading cause of sudden liver failure in the U.S.

"We're always looking for ways to better communicate information to patients and consumers," says Dr. Edwin Kuffner, vice president of McNeil Consumer Healthcare, the Johnson & Johnson unit that makes Tylenol.

Overdoses from acetaminophen send 55,000 to 80,000 people to the emergency room in the U.S. each year and kill at least 500, according the U.S. Centers for Disease Control and Prevention and the Food and Drug Administration.

Acetaminophen can be found in more than 600 common over-the-counter and prescription products used by nearly one in four American adults every week, including household brands like Nyquil cold formula, Excedrin pain tablets and Sudafed sinus pills.

Tylenol is the first of these products to include such a warning label on the bottle cap. McNeil says the warning is a result of research into the misuse of Tylenol by consumers. The new cap message will read: "CONTAINS ACETAMINOPHEN" and "ALWAYS READ THE LABEL."

The move comes at a critical time for the company, which faces more than 85 personal injury lawsuits in federal court that blame Tylenol for liver injuries and deaths. At the same time, the U.S. Food and Drug Administration is drafting long-awaited safety proposals that could curtail the use of Tylenol and other acetaminophen products.

The changes do not apply in Canada, Kayce Thomas, a spokeswoman for Johnson & Johnson said Friday. "This is something that we're continually evaluating."