A cold is a mild viral infection of the nose, throat, sinuses and upper airways. It can cause nasal stuffiness, a runny nose, sneezing, a sore throat and a cough. Usually it's a self-limiting infection – this means it gets better by itself without the need for treatment.
More than 200 different viruses can cause the common cold, which is why people will become infected again at a later stage. Read more about the causes of cold.
Adults have about two to four colds a year, and children have three to eight. A child’s immune system is less well developed compared to an adult’s, so they're more vulnerable to infection.
Women get more colds than men, possibly because they're more likely to come into close contact with children.
How a cold spreads
A cold can be spread through:
- direct contact – for example, if you sneeze or cough, tiny droplets of fluid containing the cold virus are launched into the air and can be breathed in by others
- indirect contact – for example, if you sneeze onto a door handle and someone else touches the handle a few minutes later, they may catch the cold virus if they then touch their mouth or nose
In general, a person first becomes contagious two to three days before their symptoms begin, and they remain contagious until all their symptoms have gone. So most people will be contagious for around two weeks.
Why colds occur in the winter
Colds are more frequent during the winter months. This may be because people are more likely to stay indoors and be in close contact with each other. However, higher rates of colds haven't been found in passengers on the London Underground even though they spend a lot of time in close contact with each other.
Research carried out in 2005 suggests that cold weather could make people more vulnerable to developing a cold. However, further research is required to confirm this.
Outlook
In adults and older children, the cold will usually last for about a week. You can relieve the symptoms of the cold while the body fights off the infection by taking over-the-counter medication, such as paracetamol, and drinking plenty of fluids.
Read the treating colds section for more information.
