Preventing colds and flu

Many people believe vitamin C can cure the flu and echinacea can prevent colds. But is there scientific evidence to back this up?

Can vitamin C stop a cold?

"Research has found no evidence that vitamin C prevents colds," says Dr Hasmukh Joshi, vice-chair of the Royal College of GPs.

In 2007, the authors of a review of 30 trials involving 11,000 people concluded that, “regular ingestion of vitamin C has no effect on common cold incidence in the ordinary population”. A daily dose of vitamin C did slightly reduce the length and severity of colds.

When it comes to flu, one person in three believes that taking vitamin C can cure the flu virus. It can’t.

"Studies found that vitamin C offers a very, very limited benefit," says Dr Joshi. "I wouldn't recommend it."

Does echinacea reduce cold risk?

The root, seeds and other parts of echinacea plants are used in herbal remedies that many people believe protect them against colds. There have been several studies into echinacea’s effect, but no firm conclusions.

A review of trials involving echinacea showed that, compared with people who didn’t take echinacea, those who did were about 30% less likely to get a cold. However, the studies had varying results and used different preparations of echinacea. It’s not known how these compare with the echinacea in shops.

This review also showed that echinacea did not reduce the length of a cold when taken on its own.

"There is a belief that echinacea aids the immune system, but a survey of studies in 2005 showed that it did not," says Dr Joshi. "I wouldn't recommend that it helps, but if people believe it, they can take it. There's no harm in it." Echinacea should not be given to children under 12 years old.

Find out more about a study of echinacea published in 2012 at Echinacea cold study claims analysed.

Will zinc put off a cold?

There is some evidence that taking zinc lozenges, syrup or tablets may reduce how long a cold lasts.

2011 Cochrane review of studies into zinc and the common cold suggests that taking zinc supplements within a day of the symptoms starting will speed up recovery from a cold and lessen the severity of symptoms. Long-term use of zinc isn't recommended as it could cause side effects such as vomiting and diarrhoea. More research is required to find out the recommended dose.

There has also been research into nasal sprays containing zinc. "Some people believe that the zinc lines the mucosa [the lining of the nose] and stops a cold virus attaching itself to the nose lining," says Dr Joshi. "Unfortunately, this has been found to be no more effective than a placebo."

Does getting cold or wet cause colds?

The only thing that can cause a cold or flu is a cold or flu virus. Getting cold or wet won’t give you a cold. However, if you are already carrying the virus in your nose, it might allow symptoms to develop.

A study at the Common Cold Centre in Cardiff found that people who chilled their feet in cold water for 20 minutes were twice as likely to develop a cold as those who didn't chill their feet.

The authors suggest that this is because some people carry cold viruses without having symptoms. Getting chilled causes blood vessels in the nose to constrict, affecting the defences in the nose and making it easier for the virus to replicate.

"Getting a cold from going out in the cold or after washing your hair is a myth," says Dr Joshi. "Colds are common. If the virus is already there and then you go out with wet hair and develop symptoms, it's common to think that is what caused it."

So what does work to prevent colds and flu?

The flu vaccine can prevent you from catching flu. Apart from that, the best way to protect yourself from colds and flu is to have a healthy lifestyle.  

"Eat a healthy diet, take regular exercise and drink plenty of warm drinks in the winter months," says Dr Joshi. "The important thing to remember is that most people are going to catch a cold in winter anyway, because there is no effective cure for cold viruses."  

Washing your hands will help avoid transmitting cold and flu viruses

Cold and flu viruses can be passed through tiny droplets of mucus that are sneezed or coughed out into the air by an infected person, and breathed in by another person. If an infected person sneezes into their hand, and then touches an object (such as a doorknob, or railing on a train) the virus can pass from the object to the next person who touches it. By washing your hands, you will be getting rid of any viruses you've picked up on them.

Avoiding touching your nose and eyes will help stop you getting infected

Cold and flu viruses can enter your body through the eyes and nose. If you have any infected droplets on your hands, and you touch your eyes or nose, you can pass the virus into your system. By not touching your nose and eyes, you'll reduce your chances of catching a virus.

Page last reviewed: 18/10/2012

Next review due: 18/10/2014

Ratings

How helpful is this page?

Average rating

Based on 128 ratings

All ratings

Add your rating

Comments

The 4 comments posted are personal views. Any information they give has not been checked and may not be accurate.

User825015 said on 04 December 2013

Interesting information! Alternatively, I came across a great article on why adults suffer reoccurring colds and flu’s and how to prevent them naturally. Thought it was worth a share:
http://www.drdnaturopath.com/index.php/recurring-colds-in-adults-why/
Thanks & Enjoy!

Report this content as offensive or unsuitable

lesleyW said on 13 July 2013

Not a very good article. I've been cold (and flu) free for 4 years now - by taking ascorbic acid in large doses at the first onset of symptoms or even as a prophylactic (if I'm going into crowds/public transport etc). And it works. But I'm talking about 1 whole gram taken hourly at first onset of symptoms, not miligrams. Real vitamin C would be better - but lemons are expensive (and the vitamin content dodgy), and you can only get greens from the garden in summer. Ascorbic acid is cheap when bought in bulk and I can get it as a powder (I can't tolerate the fillers etc in tablets). Unfortunately generic condemnations like this one don't make me very confident about the onset of "evidence-based medicine".

Report this content as offensive or unsuitable

jwfone said on 04 December 2011

Readers should also consider the more recently reviewed NHS Choices pages on the common cold, which reference more recent research.

Treatment
http://www.nhs.uk/Conditions/Cold-common/Pages/Treatment.aspx

Prevention
http://www.nhs.uk/Conditions/Cold-common/Pages/Prevention.aspx

Report this content as offensive or unsuitable

mgdwcb said on 22 January 2011

Unfortunately this article perpetrates the myths about adsorbate (erroneously labelled vitamin C) and turns them into straw man arguments. No substance, taken in small daily amounts, can prevent the onset of a cold or flu. This is like claiming that taking a few milligrams of Penicillin each day will prevent you catching a sexually-transmitted disease. There is the question of dosage. For over forty years thousands of people have taken adsorbate orally and intravenously and colds and flu have been either aborted or drastically reduced in severity and duration. This has been done with the full knowledge of medical doctors and in many cases under their supervision. I urge readers to do their own research.

Report this content as offensive or unsuitable

Services near you

Find addresses, phone numbers and websites for services near you

Help fight flu

Sign up for the flu survey to help researchers at the London School of Hygiene and Tropical Medicine track the spread of flu

10 myths about flu and the flu vaccine

Ten common myths about flu and the flu vaccination, and the truth behind them

5 A DAY

Whether you're cooking for a family or eating on the run, our tips and recipes can help you get your 5 A DAY

Flu jab in pregnancy

Why pregnant women should have the flu jab and where you can get the vaccine

Flu vaccine for children

The children's nasal spray flu vaccine is for two and three year olds plus children with long-term health problems

Self-help tips to help you stop smoking

Want to quit smoking? Some small lifestyle changes could help you resist the temptation to light up.

Worried about the latest health scare?

Behind the Headlines can help you sort fact from fiction on the latest health scares and miracle cures in the media

Who should have a flu jab?

Certain people are at greater risk from flu and need a flu jab, including over-65s and pregnant women