Five facts about colds

Some surprising facts about colds, including what causes symptoms such as a blocked nose, and why mucus turns thick and yellow.

1. Cold viruses don't make us feel ill

"It's your own immune response that makes you feel ill," says Professor Ron Eccles of the Common Cold Centre in Cardiff, where experts have researched the common cold for more than 20 years.

When you get a cold, the virus attacks the nose and the back of the throat, and it doesn't take long for the body's natural defences to start to work.

"The immune system detects the virus and floods the area with white blood cells and chemical messengers, and these trigger various symptoms such as headaches and a blocked nose."

2. A blocked nose is due to swollen erectile tissue

"During a cold, the lining of your nose is the battlefront," says Professor Eccles. When your nose feels blocked, it isn't because it's full of mucus, but because the blood vessels in your nose are inflamed.

The nasal lining is made from erectile tissue (similar to the tissue in the sexual organs). When you have a cold, the blood vessels swell up as infection-fighting white blood cells flood to the area. This narrows the air passage in your nose and restricts the airflow as you breathe.

decongestant spray can reduce the swelling and allow you to breathe more easily.

3. You can catch a cold through your eyes

When an infected person coughs or sneezes, they release droplets of mucus into the air, or into their hand if they use their hand to cover their mouth. If you get these droplets on your hand (for example, by shaking hands or touching contaminated objects such as doorknobs), you can pass them into your eyes or nose when you touch them.

Most of us touch our eyes and nose more often than we realise. A duct links the eyes and the nasal cavity, and the virus travels easily from the eye to the nose and throat, where it can cause infection. You can help avoid being infected by washing your hands thoroughly.

4. Women get more colds than men

"Women have more colds than men, and this is probably due to increased interaction with children," says Professor Eccles. Children get around seven to ten colds a year, compared with two to three for adults. So people who spend a lot of time with children, such as childminders, nursery teachers or school teachers, are more likely to pick up the viruses.

5. Yellow mucus is caused by white blood cells

When your immune system is fighting a cold virus, one of the first symptoms is clear, runny mucus from the nose. As the cold develops, mucus usually becomes thicker and yellow, then green. White blood cells cause this change in colour and texture as they flood to the nasal area and increase in number as the cold progresses. 

"Many people think that yellow or green mucus is caused by bacteria, but this isn't the case," says Professor Eccles. "It's because there are billions of white blood cells in the mucus."

Cold or flu?

Do you know the difference between a cold and flu? An expert explains the conditions, treatments and remedies available.

Media last reviewed: 26/05/2015

Next review due: 26/05/2017

Page last reviewed: 13/10/2014

Next review due: 13/10/2016


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The 3 comments posted are personal views. Any information they give has not been checked and may not be accurate.

3dwin said on 11 September 2015

If this video told us what the difference is between the infections like it says it would we'd be able to diagnose ourselves and wouldn't have to pester gps with our runny noses. I thought this video was supposed to help me tell the difference between a cold and the flu so far all I can tell is one is worse than the other or are they both the same? This video just spouts jargon and explains nothing how good can a doctor be when twice explaining the flu, all he has to say is it "knocks you for six". Real useful intelligent stuff. This video just proves how out of date modern medicine is.

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globalgent said on 06 December 2011

The basic fact were explained , of course knowing the enemy is half the battle. My symptoms followed the classic pattern; cold,the chest infection exacerbating my COPD.Unfortunately i couldn,t obtain any anti- biotics so i just had to grin and bear it.

Chin up

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joanadassabooth said on 04 November 2010

the video is put across well, easy understanding well done. right now i am feeling really ill the only time i get out of my bed is to visit the toilet, body is week, nose is blocked, feel hot then cold, have not managed to eat, i have a lot of medical problems, i caught this off my mum which in turn she caught hers off her grandchildren, i never really slept last night tossing and turning all the time, light headed, every so often i take mt temperature, the highest it went was 38.3 at 13:03 today and at 13:40 it was 37.8. now it's 14:46 it is now 37.2.

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