Understanding the Common Cold -- the Basics

A runny nose, scratchy throat, and nonstop sneezing -- you can't miss the signs of a cold. But mystery shrouds a lot of other things about it. Why do you seem to get them so often while your best friend stays well? And more importantly, how can you stay healthy this year? Get the lowdown on the all too common cold.

What Is It?

It's an illness caused by a tiny, living thing called a virus. More than 200 types lead to your misery, but the most common one is the rhinovirus, which brings on 10% to 40% of colds. The coronavirus is responsible for about 20% of cases, while the respiratory syncytial virus (RSV) and parainfluenza virus cause 10% of colds.

Colds cause a lot of people to stay home. The CDC says 22 million school days are lost each year in the U.S. because of them. Some estimates say that Americans have 1 billion colds a year.

For more detail, see Common Cold Causes.

How a Common Cold Starts

You can catch it from another person who is infected with the virus. This usually happens if you touch a surface that has germs on it -- a computer keyboard, doorknob, or spoon, for example -- and then touch your nose or mouth. You can also catch it if you're near someone who is sick and sneezes into the air.

A cold begins when a virus attaches to the lining of your nose or throat. Your immune system -- the body's defense against germs -- sends out white blood cells  to attack this invader. Unless you've had a run-in with that exact strain of the virus before, the initial attack fails and your body sends in reinforcements. Your nose and throat get inflamed and make a lot of mucus. With so much of your energy directed at fighting the cold virus, you're left feeling tired and miserable.

One myth that needs to get busted: Getting chilly or wet doesn't cause you to get sick. But there are things that make you prone to come down with a cold. For example, you're more likely to catch one if you're extremely tired, under emotional distress, or have allergies with nose and throat symptoms.

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Common Cold Symptoms

When a cold strikes, you may have symptoms like:

  • Scratchy or sore throat
  • Sneezing
  • Stuffy nose
  • Watery eyes
  • Mucus draining from your nose into your throat

More severe symptoms, such as high fever or muscle aches, may be a sign that you have the flu rather than a cold.

For more detail, see Common Cold Symptoms: What You Might Feel.

Kids and Colds

Children have about 5-7 colds per year. A big part of the reason: They spend time at school or in day care centers where they're in close contact with other kids most of the day. And to top it off, their young immune systems aren't yet strong enough to fight off colds.

For in-depth information, see Children and Colds.

Preparing for Cold Season

In the U.S., most colds happen during the fall and winter. Beginning in late August or early September, the rate increases slowly for a few weeks and remains high until March or April, when it goes down. The reason may partly have to do with the opening of schools. Cold weather may also play a role because it leads you to spend more time indoors, where you're in closer contact with people who are contagious.

Changes in humidity in different seasons may also affect how often people get sick. The most common cold viruses survive better when it's low. Also, cold weather may make the lining of your nose drier and more vulnerable to an infection by a virus.

When to Call the Doctor About a Cold

Most colds last about 7 to 10 days, but if your symptoms linger, you may need to call the doctor. Sometimes, colds lead to an infection by bacteria in in your lungssinuses, or ears. If that happens, your doctor may prescribe antibiotics, which work against bacteria but not against viruses.

For more detail, see Common Cold Complications.

More Questions About Colds?

Need more info about the common cold? See 10 Questions About Colds.

WebMD Medical Reference Reviewed by Jennifer Robinson, MD on March 02, 2015

Sources

SOURCES: 

National Institute of Allergy and Infectious Diseases: "Common Cold." 

Palo Alto Medical Foundation: "The Common Cold." 

University of Virginia Health System: "Upper Respiratory Infection (URI or Common Cold)." 

National Jewish Medical and Research Center: "Getting Well When You Have a Cold or the Flu." 

Medline Plus: "Common Cold." 

FDA: "Colds and Flu: Time only Sure Cure." 

American Lung Association: "A Survival Guide for Preventing and Treating Influenza and the Common Cold."

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