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A common cold is an infection of your nose and upper airways. It's usually caused by a virus. Lots of different viruses can cause a cold.

Often the first sign of a cold is a dry, scratchy sore throat.¹ You may also:

• Sneeze
• Get a runny or blocked nose
• Get a cough or a headache
• Feel generally sick.

Your cold may be caused by one of over 200 different viruses.² That's why you can get lots of colds. Even if your body learns how to fight off one kind of cold virus, you can still catch the other kinds.

When someone has a cold, the mucus in their nose is full of the cold virus. Sneezing and blowing the nose can spread the virus as tiny drops in the air. You can catch a cold by breathing in the virus. But you're more likely to catch a cold by touching something that's got cold viruses on it, such as a door handle, and then touching your nose, eyes, or mouth.³

You're most likely to pass on a cold in the first two or three days that you have it.

Children tend to have a lot of colds because the body takes time to build up immunity. So you have fewer colds as you get older. Your body learns to fight off a particular kind of virus each time you get an infection.

Adults with a lot of contact with children are also more likely to catch a cold.

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.