The common cold

It’s January: if you don’t have a cold yourself, you know someone who does.

The common cold is caused by a virus infection in the nose, although colds can also involve the sinuses, ears and bronchial tubes. Symptoms include sneezing, a runny and/or stuffed-up nose, a sore or scratchy throat, cough, hoarseness, and sometimes headaches, feverishness, chills and a general feeling of malaise.

Colds last anywhere from two or three days to two weeks, averaging about one week. Adults typically have two or three a year and children six to 10–which is why the major source of cold viruses is children’s noses.

One reason why we keep catching colds over and over, unlike some other viral illnesses that our bodies become immune to once we’ve had them once, is that more than 100 different viruses cause colds.

Although cold viruses, like all viruses (and unlike bacteria) can only multiply inside living cells, they can survive on surfaces such as doorknobs. The single best way to prevent the transmission of colds is frequent handwashing, especially after you’ve been in contact with someone who has a cold or touched a possibly contaminated surface. Keeping your fingers out of your eyes and nose also helps, as does avoiding getting coughed or sneezed on.

There are a lot of myths about colds. The greatest myth, according to the doctor-run website, is that susceptibility to a cold requires a weakened immune system. In reality, perfectly healthy people with normal immune systems are highly susceptible to the cold virus once it enters the nose. In fact, there’s some evidence that people with normal immune systems are more prone to developing symptoms once infected than people with less active immune systems, because the symptoms are caused by the immune system’s reaction to the infection.

Another myth is that you can “catch cold” by becoming cold or chilled: studies show people who are chilled are no more susceptible to colds than those who are not. Similarly, there’s no truth to the myth that central heating dries the mucus membranes of the nose and makes a person more susceptible to catching cold.

Once you have a cold, pharmacological treatments are available only for the symptoms–they do nothing to fight the cold virus itself. You can take decongestants to dry out your nose, antihistamines (but a recent analysis by the U.S. Food and Drug Administration found antihistamines helped only two in 10 cold sufferers), pain relievers for fever and headache, and cough suppressants. All-in-one cold remedies combine these drugs.

Then there are all the other popular remedies. One study has suggested that taking one gram of Vitamin C within 24 hours of the onset of symptoms does indeed have a mild beneficial effect There’s inhaling steam, either by itself or with Vicks VapoRub thrown in. (One pediatrician remembers that his grandmother used to put Vicks VapoRub down the back of his throat when he had a cold, which, he says, guarantees “you’ll never cough in front of a grandparent again.”)

Chicken soup? Well, it keeps you hydrated, and soothes a sore throat. Honey and lemon? Also soothing. Echinacea? Zinc lozenges? If they have any effect, it’s mild.

Then there’s the old saying about “feed a cold and starve a fever.” Recently a small study in Amsterdam showed that the balance of two chemicals that regulate part of the immune system shift markedly after a meal. The average level of a chemical messenger called cytokine gamma interferon (INF-y), which stimulates the body’s defence against chronic infections like colds, increased by 450 per cent after a meal. Starved volunteers, on the other hand, had low INF-y levels but far higher concentrations of another chemical called interleukin-4 (IL-4), which is associated with the production of antibodies–the front line defence against acute infections, the kind most likely to cause fevers. So maybe there’s something to that old-wives’ tale after all.

Determining which remedies work is difficult because in studies, people given placebos (pills made of starch, for instance) often report that they worked wonders on their colds. Since the length a cold hangs on can vary from a couple of days to a couple of weeks, it’s very hard for either researchers or suffers to tell whether something worked or whether the cold simply got better on its own.

But there is a sure way to avoid getting a cold at all, according to Jack Gwaltney, a leading U.S. cold researcher: “Have nothing to do with people, become a hermit.”

Try it, and let me know how it turns out–by e-mail, of course.

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