Elliot Dick and Jack Gwaltney are old soldiers in the cold wars. For more than 30 years, the pair of American researchers has subjected hundreds of volunteers to colds to find out how the viruses do their dirty work. Indeed, it was Dick who, decades ago, helped invent “killer Kleenex” – tissues impregnated with chemicals that proved impervious to cold viruses but less successful in the marketplace. And Gwaltney once went so far as to record the number of times Sunday school teachers and medical students pick their noses – as part of an experiment looking into how cold viruses are transmitted.

What can they and other researchers tell you about how best to defend yourself against a cold? And if a cold virus does penetrate your defenses, what are the best ways to keep the ensuing sore throat, clogged nose, watering eyes, sneezes, coughs, and general misery milder and shorter than the usual week or so? Here’s the latest report from the cold front.

What’s the best thing I can do to escape a cold?

Keep your nose clean – figuratively speaking, that is. If you can stop a rhinovirus from docking high up inside your nose – in the nasopharynx, where nose meets mouth – there’s no way it can make you sick. “No question,” says Gwaltney. “It’s that specific.” Since a cold virus can get there only by touch or through the air, here’s what to do:

Keep your hand away from your nose and eyes. Scratching your nose or rubbing your eyes won’t put a cold virus directly into the nasopharynx, of course. But a virus deposited at the base of the nose or in the eye can easily be inhaled higher up into the nose or drain into the nasopharynx through the tear ducts. According to Gwaltney’s own study, most people’s hands wander up to their noses or eyes at least once every three hours. Train yourself to do better, and you’ll cut down dramatically on the number of colds you catch.

Wash your hands often. Within reason, of course. You can’t wash them every five minutes, for heaven’s sake. But when you’re around other people with colds, think like Lady Macbeth. Wash at every opportunity, preferably with an anti-bacterial soap.

Move away from people who are coughing and sneezing. And if you’re the one with the cold, carefully cover your own coughs and sneezes with disposable tissues – not cloth hand-kerchiefs, which act like virus motels when they’re moist with mucus. Dick has found that keeping virus-bearing droplets from flying around goes a long way in preventing a cold from spreading. “We’ve tested a lot of couples, and we didn’t get any transmission when they were being careful,” he says.

Should I take vitamin C and other supplements?

Probably. There’s no direct evidence that vitamin C can prevent cold, but several well-controlled studies have demonstrated that it can markedly lessen both the symptoms and duration of a cold. Dick’s studies show that taking one 500-milligram tablet, four times a day, is all you’ll need.

Can my toothbrush reinfect me?

It’s not likely, for a couple of reasons. First, a rhinovirus, the most common cold virus, has to get into your nose, and what won’t happen with a toothbrush unless you have an extremely wild way of using it. Other kinds of viruses, such as enteroviruses, which live in your gut, do cause a few colds, but so few that they’re no reason to soak a toothbrush in rubbing alcohol or disinfectant. Second, once you’re infected with a cold, you produce antibodies to the virus that caused it. That gives you a grace period of at least a few weeks – maybe much longer – of resistance to that particular virus.

How risky is it to be around people with colds?

A lot less risky than you might think. Cold viruses, studies show, have to attack in overwhelming numbers to get past the hairs, mucus layers, and other mechanical barriers built into the human nose. “Twenty minutes in a doctor’s office or on a bus ride to work shouldn’t pose any great threat,” Dick says, “unless you’re near somebody with a really bad cough that puts out a lot of droplets.” Even a couple of hours at the movies is pretty safe, he says, assuming you stay three or four seats away from anyone who’s not covering up and you wash your hands before putting them near your eyes or nose.

Spending all day in an office building filled with sneezers or a couple of hours or more in an airplane is another matter. In an airplane, especially, recirculated air in a pressurized cabin distributes viruses among all the passengers and dries out mucus membranes that normally, when moist, would trap invaders and dispose of them. For that reason, one of the best things you can do is drink a lot of water.

And kissing is off limits – right?

Wrong, all wrong, says Dick. A kiss is hardly more likely to transmit a cold than is sitting in a draft, he says. As chief of the Respiratory Virus Research laboratory at the University of Wisconsin, Dick once blind-folded 13 pairs of volunteers and walked them into a sterile room. One person in each pair had been infected with a particular cold virus; the other person had neither the cold nor antibodies that might be present from an earlier exposure to defend against it. While his team of researchers watched, each pair kissed for a minute to a minute and a half. “Being blind-folded, I think, let them really put their hearts into it,” he says. Just one of the 13 smoochers caught a cold.

Getting any more passionate, however, could put you at risk. Jack Gwaltney, chief of epidemiology and virology at the University of Virginia medical school, points out that some kisses involve touching with the hands. If your hand picks up a virus and then comes in contact with your eyes or nose, he says, you might wake up a few days later with the sniffles and blame the kiss, unfairly, for the cold.

What if I catch a cold anyway? What should I do?

For starters, get as much sleep as you can to keep your immune system humming. And drink plenty of liquids – especially water – to loosen mucus and carry away the debris of infection. Beyond those basics, it’s usually best to attack symptoms individually. Here’s how:

Try decongestant drops or spray for a stuffy nose. Unlike pills, they put medication right where you need it. When you’re aiming at your nose, why run a drug through your stomach? Decongestants are a good bet for the worst night or two, when stuffiness ruins your sleep. But don’t use them more than three nights in a row, because rebound swelling can stop you up all over again.

Give antihistamines a try. Until recently, experts warned that histamines – chemicals released in allergic reactions – have little to do with cold symptoms. That advice was based partly on Gwaltney’s own reports that he detected no histamine in nasal secretions. “However, science marches on,” he says. In a more recent study, not yet published, he finds that for people with rhinovirus colds, antihistamines reduced sneezing by about 50 per cent and runny noses by about 30 per cent.

Stop a cough with codeine or an over-the-counter suppressant containing either dextromethorphan or diphenhydramine chloride. All the drugs work by soothing the brain’s cough centre. Gwaltney has also reported success with naproxen, a non-steroidal anti-inflammatory drug. He speculates that it works by interfering with prostaglandins, hormone-like substances that trigger inflammation and coughs. Ibuprofen, another anti-inflammatory found inn pain-killer pills, also reduces coughing. Use these drugs in the minimum over-the-counter doses.

For a sore throat, try gargling with a teaspoon of salt dissolved in a glass of warm water. The salt-water won’t kill viruses or bacteria, but it will reduce inflammation and take the edge off the pain. Gargling also helps wash away irritating secretions left by post-nasal drip.

How can I be sure I have a cold and not an allergy or the flu?

It’s a matter of degree. A cold usually comes on gradually, with a vague out-of-sorts feeling. Then, in a day or so, you’ll typically notice a slight sore throat, followed by a symphony of problems in your nose, throat, and chest. If you feel chills or aches, they’ll be slight, and your fever, if any, probably won’t top 100°.

An allergy can mimic a cold, but it’s much less likely to cause a fever, and it is never accompanied by aches and pains. If your eyes and nose itch like crazy, suspect an allergy.

Influenza strikes fast, with fever, aches – mainly in the back muscles – sore throat, and a dry cough worse than you get with most colds. The fever usually hits the 101° to 102° range, and it sometimes flames as high as 104°, often so quickly that you’ll recall the exact hour it began. Other symptoms may include runny nose, headache, eye pain, and sensitivity to light, as well as diarrhoea and vomiting. Even if you’re the type of person who goes about your business with a cold, you’ll probably find that impossible with the flu.

Will chicken soup help?

It appears so. Irwin Ziment, a pulmonary specialist at the University of California at Los Angeles, points out that chicken, like most protein foods, contains natural amino-acid called cysteine, which is released when you make the soup. “Cystine bears a remarkable chemical similarly to a drug called acetylcysteine, which doctors prescribe for their parents with bronchitis and respiratory infections,” he says. Acetylcysteine, which originally was made from chicken feathers and skin, thins out mucus in the lungs and make it easier to expel, he says. Ziment advises his patients to make their soup as hot, spicy, and garlicky as they can stand. Pepper, hot curry powder, and other spices release a wave of watery fluids in the mouth, throat and lungs, thinning out mucus.

When is cold most infectious?

For the first three days, from the time the first symptom appears. “You start sending a lot of viruses into the outside world when your nose is running and you’re coughing and sneezing,” Gwaltney says. During those three days, your body’s defenses are working to knock down the number of viruses, and by the fourth day, you pose less danger to people around you.

How long should I expect my cold to last?

It depends. Most people are completely over a cold’s symptoms within 10 days. But the illness can last anywhere from three days for a lucky few to several weeks.

If yours hasn’t improved after 10 days or seems worse, call a doctor. Call sooner if you notice facial swelling or super-sensitive molars – signs of bacterial infection in the sinuses or middle ear. You can attack that, unlike, the original viral infection, with antibiotics. You don’t always have to – such infections often clear up by themselves – but you should, for two reasons: to get rid of pain and debilitation and to reduce the risk of the cold’s turning into a sinus infection that might last months or years.

What else should I do?

Stay cheerful. Watch funny video movies. Call a friend you haven’t talked to in years. Visualize viruses keeling over and dying. Remind yourself, aloud if necessary, that this illness is no big deal.

You’re not just whistling in the dark when you do all that. You’re helping your immune system shorten the cold. Sheldon Cohen, a researcher at Carnegie Mellon University in Pittsburgh, found that the more positive a person’s attitude – measured by responses to questions about stress from volunteers at the Common Cold Research Unit in England – the less his or her chances of catching a cold in the first place, and the less severe the symptoms if a cold did appear.

Look on the bright side, in short, and you’ll improve your chances of avoiding a cold or, if you run out of luck, at least getting over it fast.