The People versus Extra-Strength Tylenol is a case without precedent. No mass murderer, until now, has seized on a popular product as his murder weapon. No product has ever disappeared so suddenly and dramatically from so many millions of homes and stores.

But as public relations and marketing experts size up the Tylenol killings and Johnson & Johnson's reaction, they need not form their judgments in a vacuum. They can and do draw on the painful lessons of dozens of other companies and products that, over the last two decades, have had to defend themselves in trying or tragic circumstances.

Beginning with the great cranberry scare of 1959, American businesses have endured a series of crises over the Chevrolet Corvair, tuna fish, Bon Vivant vichyssoise, the Firestone 500, the Ford Pinto, the DC10, the Rely tampon and others.

The future of Tylenol is a question the experts come down on both sides of. Some think it is doomed to go the way of the Corvair and the Bon Vivant line of canned soups, whose producers tried and failed to persuade the public that there was no longer anything to fear. Headlines about instant death, said Stephen Greyser, who teaches marketing theory at Harvard Business School, have a far more profound effect on most people than any number of studies showing more probable but gradual health consequences, such as the incidence of lung cancer among smokers.

With Extra-Strength Tylenol, said Greyser, "it's very easy for the consumer to say, 'Holy moly, this could happen to me tomorrow!' "

But others see Tylenol's predicament as closer to that of the DC10 after the 1979 Chicago air crash in which an engine mount broke and 278 people died. Although wide-body airplanes have been slow sellers generally over the last few years, the public seems to have accepted the Federal Aviation Administration's finding that the Chicago crash was basically the result of maintenance procedures rather than any defect in the plane itself.

The DC10/Tylenol analogy also includes the role of an intermediate player between the manufacturer and the public -- the airlines in one case, and the medical profession in the other. After the Chicago crash, airline officials were "staunch defenders of the airplane and staunch critics of the press," according to John Cooke of McDonnell Douglas, whose Douglas Aircraft subsidiary makes the DC10.

Tylenol built its extraordinary $400-million-a-year sales volume and 37 percent share of the pain-reliever market through an aggressive marketing campaign aimed at doctors. So the typical Tylenol user is "very dependent on the opinion of the professional," to quote one marketing expert with long experience in the pharmaceutical field. If doctors renew their endorsement, he speculates, their patients could well fall in line.

The fervent loyalty of some Tylenol users is documented by the experience of a high executive at the Bristol-Myers Co., who tried and failed to persuade his mother to abandon Tylenol in favor of Bristol-Myers' Datril, a competing version of the same aspirin substitute, acetaminophen. Just as the patient-doctor bond proved stronger than the mother-son bond in this case, it has been credited with keeping Datril sales down around 3 percent of the pain-reliever market to date.

Endorsements have always been an option for the company out to win back public confidence in a tainted product. After the Food and Drug Administration put the nation on alert about the presence of a carcinogenic weed-killer in some of the 1957, 1958 and 1959 cranberry crops, it became de rigueur for potential presidential candidates not only to belittle the danger but to consume cranberries at every opportunity. A few weeks before Thanksgiving 1959, Richard M. Nixon had four helpings of cranberry sauce at a testimonial dinner for Rep. Melvin Laird, held in the cranberry-growing community of Wisconsin Rapids, Wis. On the very same night John F. Kennedy ate cranberries at a political function 31 miles away in Marshfield, Wis.

"I see no reason for hysteria over cranberries on any consumer's part," Nixon declared. "I am certain the Department of Health, Education and Welfare is working rapidly to separate those comparatively few contaminated cranberries, and I, like other Americans, expect to eat traditional cranberries with my family on Thanksgiving Day." Kennedy echoed similar sentiments, minus the plug for the Eisenhower administration. (Only Hubert Humphrey sounded an incongruous note, attacking certain nameless politicians for practicing "cranberry politics" and vowing not to "turn phony for political advantage.")

After the DC10 disaster, the manufacturer considered hiring Bo Derek and Jane Fonda as spokeswomen, before deciding on former astronaut Pete Conrad, who was already a company executive. Conrad became the star of an intensive six-month series of advertisements in which he invited concerned passengers to send in for a free booklet about the DC10 and its safety record. Some 470,000 of the booklets were mailed out, and "we reduced to some considerable degree the existing passenger resistance to the DC10," said Cooke. "It got down to a level comparable to that of other airplanes. Now would it have gone down anyway? I don't know."

The DC10 debate was a case in which the maker fought back hard against what it saw as unwarranted charges and disproportionate press coverage. "I think the publicity that followed that accident was the world's most extensive brainwashing in history," Douglas Aircraft President John C. Brizendene said at the time.

The tuna fish industry took an even more aggressive stance after the FDA ordered a national withdrawal and emergency analysis of all canned tuna in December 1970, because mercury levels in some tuna lots exceeded the then-standard maximum of 0.5 parts per million (later lowered to 0.1 ppm). Industry officials bitterly complained that the FDA standard was "an arbitrary guideline . . . based on nothing other than a guess," in the words of Hal Kierce, who handles public relations for the Tuna Research Foundation.

The tuna industry was also bitter about how the press handled the issue. "I got my feet wet in the tuna industry just about this time," Kierce said, "and when the announcement was made on December 15, it got massive coverage. But the February 15 announcement that everything on the shelf was hunky-dorey was somewhere on page 32 and it was a two-paragraph story in the New York Daily News ." CBS-TV, Kierce adds, ran a news story illustrating the controversy with graphic footage of Japanese victims of massive mercury poisoning. But later, in response to industry criticism, CBS aired a correction in which it acknowledged that the mercury levels had been many times higher in the Japanese case.

The demand for tuna fish dropped about 50 percent in the wake of the mercury uproar, according to Kierce, and took a year to return to normal. He attributes the revival partly to an "intensified marketing effort" and partly to tuna fish's long-term popularity. "My wife and my mother always had tuna on the shelf. Of course in my mother's day Friday was fish day for the R.C.'s Roman Catholics and we always had tuna, and then the pope changed the drill. But habits live on."

Tuna fish also had the advantage of being an inexpensive, long-lasting food. "If there is no alternative, time will heal all wounds," said one marketing expert. "Where there is a ready alternative -- perhaps in the case of the Corvair -- people can switch without any penalty."

A year was also how long it took cranberry sales to be revived, according to Christine Masclee, director of communications for Ocean Spray, a cooperative owned by 700 cranberry growers and 100 citrus growers. But the industry suffered a huge loss in 1959 because the alarm had been sounded just before Thanksgiving. Much of the loss, however, was covered by a $10-million federal-government indemnification program, reflecting the cranberry growers' argument that they had been the victims of "overreaction on the part of HEW."

The cranberry scare had an unexpected spinoff effect. Two polls of the cranberry's "public image" helped persuade the industry that it was too dependent on the Thanksgiving and Christmas trade. The result was the rise of cranberry juice and drinks for year-round consumption. "It prompted us to take a much closer pulse of consumers," said Masclee, "and see where the market was and where we should grow."

In all these cases, producers have shied away from using advertisements to respond squarely to the charges. "The decision was not to hit the issue directly but just to present tuna as a very nutritious, protein-rich, low-calorie and low-cholesterol food," said Kierce. "We reinforced all the positives."

But in one bizarre case, the manufacturer felt it had no choice but to put the issue before its customers as conspicuously as possible. The manufacturer was the Life Saver Co., and the problem was an unfounded rumor that spiders' eggs had been found in Bubble Yum, a Life Saver product. The rumor hit just when Bubble Yum was going through "almost a breakthrough in sales achievements," recalled Robert Denny, Life Saver's vice president of product management. Within 10 days, company surveys showed that "well over half" of the children in the New York area had heard the rumor, according to Denny, "and despite recommendations by some public relations people to ignore the rumor and talk about the positive benefits of the product, we chose to run an ad in all the newspapers. "Somebody is telling very bad lies about a very good product," the headline proclaimed.

As a result, the rumor faded, and years later Bubble Yum remains the best-selling brand of bubble gum in the nation.

Retired public relations man Bob Cherneff worked on the problems of saccharin, another example of industry's going on the offensive. "We mounted a campaign," he recalled, "to bring to the attention of the decision-makers -- in this case, the congressmen -- the whole question of how reliable the data were, and the importance of this substance to such large groups of people in our body politic -- the diabetics and the people who were constitutionally, physiologically overweight, the diabetic teen-agers and the overweight teen-agers who wanted to be able to do the teen-age things.

"One of the first things we did -- and of course this was a gimmick -- was to translate into human terms what the rat dosage would mean. We came up with a photograph of a person in a room literally inundated with packages of saccharin. Another thing we did was to make sure to the best of our ability that those scientists who doubted the efficacy of the tests on which the FDA was basing its action -- and they weren't Humpty Dumptys either -- that their voices were heard."

What all this history means for Tylenol and Johnson & Johnson is debatable. But whatever course the company follows, and whatever the ultimate result, J&J has already won high marks for corporate valor under fire and for applying these principles:

* Be Straightforward. "When you've got a disaster," said Jon Jessar of the Washington public relations firm Bob Gray and Co., "you've got to be out front and be honest. The people at Johnson & Johnson have done a good job up to this point. Their spokesmen have been very human. They have not attempted to get out and protect the product." By contrast, the proprietors of Bon Vivant Soups and of the Three Mile Island nuclear plant are widely faulted for coming across as defensive in their moments of crisis.

* Act Fast. "Within an hour after [Johnson & Johnson] heard about the first alert from the health examiner," said communications consultant Ed Gottlieb of Chester Burger and Co., "they undertook to notify the entire Chicago press. That is the kind of action that these situations call for."

* Put the Problem in the Best Focus. "It's clearly in Johnson & Johnson's interest to have consumers feel that it's more of an industrywide problem, even though at the moment it's just Johnson & Johnson's problem," said Harvard's Stephen Greyser. "Tylenol happens to be a brand that for one reason or another was selected by an apparently aberrational individual. It didn't have to be Tylenol, necessarily, unless it turns out to be a disgruntled employe. So it's really a secure-packaging issue that goes beyond any one brand. And from a strategy point of view, I think one of the things the company should be doing is to press for an industrywide program of more secure, tamper-proof packaging."

No one is predicting that Tylenol will return to national favor anytime soon, or without a hard struggle. "Whether they can continue to market a product called Tylenol or whether they have to dump it and start with another product is questionable," said Cherneff. But two factors could be in Johnson & Johnson's favor. One is sheer size. "If this were a single-line company," said Greyser, "there wouldn't be enough time to have the recovery happen." With $5.4 billion in over-all sales last year, however, Johnson & Johnson can afford to take the long view -- unlike, for example, Bon Vivant Soups Inc., which went bankrupt only a month after its vichyssoise was implicated in the death of a New York man and the FDA ordered the recall of more than a million cans of soup.

The other favorable factor is the sheer number of product-disasters American consumers have experienced. "People are a little more sophisticated about products," said Kierce. "There isn't this sheeplike aversion. They've been through a lot of scares."