The common cold is caused by a viral infection. More than 200 viruses can cause a cold, however, the most common viruses that cause the common cold are rhinoviruses, coronaviruses, and adenoviruses.
These viruses spread through the air when an infected person talks, coughs, or sneezes, and they can also spread by touching a surface or object that has the virus on it and then touching your mouth, nose, or eyes.
Risk factors
These factors can increase your chances of getting a cold:
- Age. Infants and young children are at greatest risk of colds, especially if they spend time in child care settings.
- Weakened immune system. Having a chronic illness or otherwise weakened immune system increases your risk.
- Time of year. Both children and adults are more likely to get colds in fall and winter, but you can get a cold anytime.
- Smoking. You’re more likely to catch a cold and to have more-severe colds if you smoke or are around secondhand smoke.
- Exposure. Having close contact with someone who has a cold will risk you catching a cold too. If you’re around crowds, such as at school or on an airplane, you’re likely to be exposed to viruses that cause colds.
Complications
A cold is not usually serious, and colds mostly disappear after 7–10 days. Sometimes, however, complications can occur. These are most likely to affect those with a weakened immune system. They include:
- pneumonia
- acute bronchitis
- bronchiolitis
- croup
- otitis media (middle ear infection)
- strep throat
Remember that, most colds last about 7 to 10 days. If your symptoms linger on, you may need to call the doctor. Sometimes, colds lead to an infection by bacteria in in your lungs, sinuses, or ears. If that happens, your doctor may prescribe antibiotics, which work against bacteria but not against viruses.