“CIGARETTE smoking is a health hazard of sufficient importance in the United States to warrant appropriate remedial action.” It was 50 years ago this month that America’s surgeon-general sounded that warning, marking the beginning of the end of cigarette manufacturing—and of smoking itself—as a respectable activity. Some 20m Americans have died from the habit since then. But advertising restrictions, smoking bans and stigma have had their effect: the proportion of American adults who smoke has dropped from 43% to 18%; smoking rates among teenagers are at a record low. In many other countries the trends are similar.

The current surgeon-general, Boris Lushniak, marked the half-century with a report on January 17th, declaring smoking even deadlier than previously thought. He added diabetes, colorectal cancer and other ailments to the list of ills it causes, and promised “end-game strategies” to stamp out cigarettes altogether.

Were that to happen America’s three big tobacco firms, Altria, Reynolds and Lorillard, could be snuffed out, too. Public-health officials plot the same fate for multinationals that supply other markets. The hit list includes Philip Morris International (PMI), which along with Altria makes Marlboro, the top-selling global brand; Japan Tobacco; and British American Tobacco and Imperial Tobacco of Britain.

They are a hardy bunch, unlikely to be spooked. But the methods they have used to withstand a half-century of battering by regulators may be losing potency. In the rich world, where the economy is sluggish, smokers are trading down to cheaper puffs. The regulatory climate in developing countries is becoming more hostile. New technologies such as e-cigarettes promise to deliver nicotine less riskily. Big tobacco firms may master them, but it would be a radical shift, akin to converting the car industry from internal-combustion engines to battery power. David Adelman of Morgan Stanley, an investment bank, does not “see anything that’s upending the conventional tobacco business model.” But the model needs tweaking.

Some reasons for Mr Adelman’s confidence are sound. Advertising bans and the industry’s pariah status deter would-be competitors. When cigarette-makers raise prices, smokers cough up. Global consumption keeps rising, thanks largely to population growth in poorer countries. The cigarette giants pamper investors with big dividends and share buy-backs; they have flocked to tobacco shares (see chart).

But the going is getting tougher. This month health officials in China, home to more smokers than any other country, called for a ban on smoking in public places. That would mainly affect state-owned China Tobacco, which has a near-monopoly. But multinationals’ shares wobbled anyway: the proposed crackdown could portend tighter regulation elsewhere. Britain’s government, after some wavering, may now go ahead and copy Australia’s requirement for cigarettes to be sold in ugly, scary “plain packs”.

Such pleasure-pinching regulation strikes at one of the main ways cigarette companies boost profits: converting smokers to pricier brands. “Premiumisation” is still happening in developing countries, where incomes are rising. But elsewhere smokers are turning to cheaper brands or rolling their own cigarettes. Many smokers will not trade back up once the economy improves, largely because smoking and advertising bans have robbed the habit of its air of glamour. Euromonitor International, a research firm, forecasts that everywhere except in Asia and the Middle East prices will rise less from 2012 to 2017 than they did during the previous five years.

Shane MacGuill of Euromonitor sees in all this “a very serious threat to the long-term health of the tobacco industry.” This is spurring a quest for safer methods of supplying smokers with their nicotine fixes. Most of the hype is about e-cigarettes, which give users a hit of vapour infused with nicotine but none of the other, nastier ingredients of tobacco smoke. In America, the fastest adopter, sales have jumped from nearly nothing five years ago to at least $1 billion in 2013.

At first, it looked as if e-cigarettes might lure smokers from the big tobacco brands to startups such as NJOY. But incumbents have been quick to see the threat. Lorillard acquired Blu, now the biggest American brand, in 2012. Altria and Reynolds are expected to launch e-cig ventures nationwide this year. Imperial recently acquired the e-cigarette operations of Dragonite, a Chinese firm that pioneered the technology. Though not the first movers, tobacco companies have bigger war chests, more knowledge of smokers’ habits and better ties to distributors than the newcomers.

Some pundits reckon Americans will puff more e-cigarettes than normal ones within a decade, but tobacco folk are sceptical. E-cigs account for just 1% of America’s cigarette market. In Europe 7% of smokers had tried “vaping” by 2012 but only 1% kept it up. PMI has higher hopes for a new type of cigarette, which heats tobacco rather than burning it. Such cigarettes could deliver fewer toxins than conventional sticks and more pleasure than mere vapour. PMI says it will invest up to €500m ($677m) in a factory in Italy to make them.

Earlier efforts to hook smokers on heated tobacco flopped, so there is no assurance that PMI’s versions will succeed. And no one knows what sort of restrictions regulators will eventually place on “reduced risk” products, including e-cigarettes.

If they can manage the transition to less harmful smokes, and convince regulators to be sensible, the tobacco giants could keep up the sort of performance that has made their shares such a fine investment over the years. But some analysts are not so sure. Many tobacco firms “are struggling to deliver the consistency of the earnings-per-share model we’ve seen in the past,” says David Hayes of Nomura. If that persists, investors may fall out of love with the industry. A half-century after the surgeon-general’s alarm, they, and incorrigible puffers, are its last remaining friends.