TRENTON, New Jersey — Tylenol, originally a pain reliever for children, has hit middle age.

The world's best-known acetaminophen brand turns 50 on Tuesday, and it's more popular than ever, in part because of its reputation as the safest nonprescription pain reliever. Even a fatal 1982 poisoning scare barely hurt the brand — and introduced tamperproof packaging.

In 70 percent of U.S. households, Tylenol now is seeing sales jump amid concern over the risks of other painkillers. Sales have grown by double digits since last fall, according to Tylenol maker McNeil Consumer & Specialty Pharmaceuticals.

"It's become the fastest-growing pain reliever in 2005," said Ashley A. McEvoy, general manager of McNeil Consumer, part of healthcare conglomerate Johnson & Johnson.

Tylenol sales are up about 9 percent in 2005's first nine months, after holding or declining slightly the three years before, according to Chicago market research firm Information Resources Inc. Sales last year totaled $786.5 million, but IRI doesn't track sales to hospitals, nursing homes or Wal-Mart stores.

One reason for growing sales is that since September 2004, popular prescription painkillers Vioxx and Bextra were pulled from the market because of increased risk of heart attack and stroke. Earlier this year, the Food and Drug Administration warned other anti-inflammatory drugs carry such risks.

Tylenol is in a separate drug class from anti-inflammatories such as Vioxx, ibuprofen and naproxen. Compared with those drugs and aspirin, Tylenol is less likely to interact with other medications, irritate the stomach or cause internal bleeding, and its safe for patients with heart disease and diabetes.

Despite J&J's aggressive marketing, Tylenol is not the best choice for arthritis pain because it does not reduce inflammation, said Dr. Michel Dubois, director of research at the New York University Pain Management Center. It also has a rare risk of liver damage at very high doses.

A Harvard study released in August also found that Tylenol increased the risk of blood pressure problems in women. The research — which involved 5,123 women participating in the Nurses Health Study at Harvard Medical School and Brigham and Women's Hospital in Boston — found that aspirin still remains the safest medicine for pain relief.

Tylenol's biggest challenge, the 1982 cyanide tampering scare in Chicago that killed seven people, is considered "a case study of how to deal with a brand crisis," said Mark Bard, president of Manhattan Research. He said pharmaceutical companies such as Vioxx maker Merck & Co. and Bextra maker Pfizer Inc. "could learn some lessons from what happened 20 years ago."

J&J had its sales force remove 264,000 Tylenol bottles from Chicago-area stores; consumers also were urged to return any Tylenol they had for a safe bottle, and prompt alerts from J&J and the FDA kept the public informed, recalled Dr. Anthony Temple, head of medical affairs for McNeil Consumer in 1982.

The culprit was never caught, but McNeil prevented a recurrence by developing containers protected by multiple seals.

"They made tamperproof packaging, which we take for granted today" on everything from nonprescription drugs to pickle jars, Bard said.