To banish a cold, kiss a mouse, said Pliny the Elder. The notion evidently didn't catch on with the pharmaceuticals firms of first-century Rome, and Pliny took to studying volcanoes instead. But when it comes to finding a cure for the West's most ubiquitous malady, the depressing truth is that almost 2,000 years later, medical science - despite having eliminated a raft of killer diseases - remains pitifully close to the rodent-snogging stage.
Take two aspirin and go to bed, say beleaguered doctors. Starve a cold and feed a fever, said your grandmother, unless she said it the other way around. Inhale steam; consume gallons of orange juice; work up a sweat, says folk wisdom. Drink vast quantities of beer, say others. Eat garlic. Kiss a mouse.
The reasons for our ignorance are simple enough. The 400,000 colds that afflict the British population at any one moment - on average, we suffer a traumatising 210 of them per lifetime - are the work of more than 200 different viruses. Over a third remain unidentified; the rest are so diverse - and mutate so rapidly - that a vaccine remains a pipe dream. Last week pharmaceuticals giant SmithKline Beecham launched a weekly cold and flu risk scale, using information gathered from eight regional centres. The Guide to Cold and Flu accompanying the scale's launch recommends a wide range of powders, mixtures and lozenges manufactured, somewhat unsurprisingly, by Beechams.
It's the nasty strain known as coronaviruses that are to blame for autumn's annual deluge of mucus in homes, schools and workplaces everywhere. There are at least four other common strains, and according to the US National Institute of Allergy and Infectious Diseases (Niaid), the combined effects of these debilitating bugs costs 44 million school and work days each year in America alone. Yet still we speak dismissively of "just a cold": no wonder the more self-pitying among us feel compelled to mutter darkly about flu and nameless "viruses" to lend credibility to our symptoms.
Yet there's nothing insipid about the cold viruses themselves. Human immune systems in the industrialised West have evolved to cope with them: sneezing, runny noses and sore throats are not directly caused by the invading bugs - they are the manifestations of the body's attempts to flush them out. But for remote populations brought into contact for the first time with the "common" cold and similar infections, the results can be catastrophic.
So why do the floodgates open when the cold weather arrives? Nobody really knows, according to Professor Ron Eccles of the Common Cold Centre at the university of Wales in Cardiff, the only research institute of its kind in the world. The viruses may flourish in winter's less humid air; low temperatures can also cool the nasal passages, rendering them less resistant. The start of the school and university term provides increased opportunities for infection too.
But one thing that's certainly not true - no matter what your grandmother said - is the idea that the cold itself causes colds. Niaid-sponsored researchers have repeatedly found that neither the development nor the severity of colds is much affected by sufferers having been uncomfortably cold - or over heated, for that matter. Even how regularly you exercise and how healthily you eat don't seem very reliable predictors of resistance or susceptibility. Indeed, too-vigorous exercise may actually increase your chances of joining the soggy tissue brigade: one study, at the 1987 Los Angeles marathon, found that 13% of runners became ill within a week, compared with 2% who had trained for the race but decided not to run.
On the other hand, the medical establishment now agrees, lack of sleep, excessive fatigue, psychological stress and the menstrual cycle all have a role to play in who falls victim to the cold. Age, too, is crucial: children typically get 6-10 colds a year; the over-60s get away with less than one a year on average.
Folk wisdom takes a hammering on the matter of treatments as well: inhaling steam from a bowl of boiling water, for example, may temporarily reduce nasal congestion, but it won't shorten your illness. Neither, according to current American research, will the consumption of industrial-strength vitamin C tablets. They may even be worse than useless: vitamin C overdoses can provoke diarrhoea, a cause for serious concern if you're very young or very old.
And the vast range of non-prescription remedies available from chemists' will do nothing to prevent, cure or even shorten bouts of cold, Niaid insists - though they may make the journey back to health a slightly less painless one. Antibiotics are a bad idea too, except where colds lead to secondary infections such as pneumonia.
Gargling with salt water is just about the only time-honoured "remedy" that passes the tests of modern medicine, though steering clear of dairy products is widely held to be a good idea too, since they stimulate the production of mucus. The best treatments are, sadly, the most boring: plenty of rest, plenty of fluids, the odd aspirin and a small amount of exercise. Professor Eccles recommends hot drinks - which make the body uncomfortably warm for cold viruses, and stimulate salivation - and spicy foods.
The best advice - markedly unhelpful to those already snuffling into their sleeves - is to develop a resilient immune system so that you don't succumb in the first place, by staying fit, eating plenty of fresh fruit and veg, and being happy: laughter boosts immunity. And to take the wilder claims of grandmothers and drugs firms alike, as a rather more enduring motto of Pliny the Elder's puts it, addito salis grano: with a pinch of salt.
• Next week: Oliver Burkeman gives the low-down on influenza
