Dos and don’ts for common colds

By David Robson12th December 2014

Many of the methods advised to ward off the common cold are based on pseudoscience rather than fact. David Robson looks at what works and what doesn’t

Covering your chest with brown paper and vinegar, soaking your feet in hot water, or wearing wet socks – the old cures for the common cold can seem laughable in light of modern medicine.

Yet the apparent benefits of many of the treatments we take for granted today – such as dosing up on vitamins or snorting salt water – evaporate under scrutiny. So what works and what doesn’t? BBC Future has sifted through the evidence to find out.

Don’t dose up on vitamin C (but perhaps boost your zinc)

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“The first thing that many people will try is to supplement their diet with vitamins C and D,” says Michael Allan at the University of Alberta in Canada, who recently reviewed the evidence for the most popular remedies. “But the evidence is terrible for those.” Dosing up on vitamin C has been shown to mildly protect people under great physical strain– such as marathon runners – from falling ill, but for the average person it reduces your risk by just a 3%. “If an adult gets two colds a year, you’ll only avoid one cold in 15 years,” says Allan.

Zinc lozenges may have a firmer footing. Based on three clinical trials, Allan says that children taking regular zinc supplements will suffer roughly 1 to 1.5 fewer colds a year, on average – compared to the six to eight that is normal for school children. There is also some evidence that it can reduce the duration of a cold by a day or so. Given that zinc tastes unpleasantly astringent, and you would need to take it all year round for the full benefit, Allan is unsure if he would recommend it for general use.

Do enjoy a tipple… maybe

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Perhaps we see it as a form of penance. It’s commonly held wisdom is that a night on the booze will weaken your body’s defences and make you open to attack from viruses. The question has not been widely explored by doctors, but three independent studies suggest that regular (but moderate) drinkers are in fact less likely to catch a cold. Your tipple of choice seems to matter – wine helps whereas beer does not. Even so, this is only preliminary evidence and should be taken with reasonable scepticism, but it at least suggests that you need not blame self-indulgence for your suffering.

Don’t take antibiotics, but do consider cold relief pills

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Put bluntly, there is no reason why antibiotics should help – since they target bacteria, whereas it is a virus that causes a cold. “There’s no real benefit from antibiotics, but they do increase the risk of adverse events like diarrhoea,” says Allan. Your best bet is to try to reduce your symptoms. Over-the-counter pills that combine antihistamines with decongestants or painkillers help relieve some of the nastier symptoms for adults (not children). But even then, the benefits are often modest and probably differ between people, and the particular types of infection they are suffering from, says Allan.

Do take a spoonful of honey (but beware other herbal remedies)

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In general, herbal remedies – such as echinacea, or garlic tablets – fail to deliver the goods. The only one to show any promise is honey. A spoonful, taken straight before bed, was found to soothe a cough in three different studies, and proved better than other sugary drinks and cough syrups. Even so, the remedy has mostly been tested on children (although one study suggested that a combination of honey and coffee could help clear persistent cough in adults.) And the mechanism is far from clear. “But with good research [behind it], I think it’s reasonable to try,” Allan says.

Finally… ask for some TLC

The people that surround you may just determine how quickly you recover. Patients who report feeling greater empathy from their doctor seem to get over their illness more quickly, an effect that can be seen both in their own reports of the symptoms, and more objective measures of their immune activity. It’s not clear if the same is true of people closer to home, but in the absence of a miracle cure, a little compassion is not much to ask – and might just provide solace where the other remedies have failed.

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There are plenty of other questions that could be explored with further research. When travelling on a crowded bus, for instance, is it better to have the windows open, to flush out all the germs, even if that means everyone gets a chill? Such questions are very difficult to study scientifically with any precision. But by far the best measure, says Allan, is to simply use your common sense – wash your hands regularly and don’t share drinks with people who are already infected. It’s not the panacea we may all be waiting for, but sometimes the simplest answer is also the most effective.

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