Common Cold

The common cold is the ordinary name of a group of commonly occurring viral infections of the upper respiratory tract * . Other terms for the common cold include nasopharyngitis (NAY-zo-fahr-en-JY-tis), rhinitis (rye-NYE-tis), and acute coryza (ko-RYE-zuh).

The common cold is a viral infection of the nose and throat characterized by sneezing, coughing, a sore throat and runny nose, headache, and watery eyes. More than 200 different viruses * can cause colds. Rhinoviruses are responsible for up to one-third of all upper respiratory (RES-puh-ruh-TOR-e) infections. Other common viruses that lead to stuffy heads and runny noses include adenoviruses, coronaviruses (ko-ro-nuh-vy-rus-sez), parainfluenza (pair-uh-in-floo-EN-zuh) viruses, respiratory syncytial (sin-SIH-she-ul) virus, coxsackieviruses (kok-SAH-kee-VY-ruh-sez), echoviruses (EH-ko-VY-rus-sez), and influenza (IN-floo-EN-zuh) viruses (although influenza may also trigger more serious complications).

As many as a billion colds occur each year in the United States. The National Center for Health Statistics (part of the Centers for Disease Control and Prevention) notes that on a yearly basis, close to 22 million school days are lost due to illness from colds, and 45 million days are spent resting while recovering from colds.

Children get colds most frequently, in part due to their close contact with so many other children in day care or school. Younger children are more likely to cough without covering their mouths and fail to wash their hands after sneezing.

In North America, young children in day care may catch several (sometimes as many as 10 or more) colds each year. People tend to get fewer colds as they grow older because they develop immunity * to some of these viruses after being infected with them. For this reason, healthy adults average two to four colds a year, and those over age 60 tend to get even fewer.

Colds are very contagious. In general, they are most contagious during the first few days of illness, when such symptoms as congestion (stuffy nose) and sneezing are starting. Cold viruses often spread through direct contact. Shaking the unwashed hand of someone with a cold who has just touched his or her face can easily spread the virus. When an infected person laughs, sneezes, or coughs, virus-packed droplets of moisture from the person's mouth and nose can be suspended in the air and inhaled by others. Sometimes these drops of respiratory secretions fall on surfaces such as kitchen or bathroom counters, where they can infect the next person who touches the surface.

Cold symptoms usually appear within two to three days after the person becomes infected. They often include a runny or stuffy nose, watery eyes, coughing, mild muscle aches, tiredness, headache, a low fever, and a scratchy sore throat. Sneezing and coughing up mucus * are also common.

Doctors diagnose colds based on a history of symptoms and findings from a physical examination. Cultures * and other tests for the viruses are available but are not done in most situations. However, the doctor will want to distinguish a cold, which is caused by a virus, from bacterial infections of the sinuses or throat such as strep throat.

Because viruses cause colds, antibiotics are not useful in fighting these infections. Some antiviral drugs may be effective in fighting some cold-causing viruses (including some rhinoviruses). Research on these medicines in coming decades may change the treatment of colds in the future.

Sometimes colds can cause swelling and irritation in the nasal passages, eustachian tubes * , and air passages leading to the lungs. Bacteria that invade the body can flourish in these areas, causing additional infections. This is why it is not uncommon for someone to develop sinusitis * , an ear infection (otitis, o-TIE-tis), or bronchitis at the end of a bad cold. For those with weaker immune systems, such as the very young, the elderly, or those with chronic illnesses, these secondary infections can lead to severe bronchitis or pneumonia, which may sometimes be life-threatening. Colds can also trigger flare-ups or worsening of respiratory symptoms in people who have asthma * .

To lower the risk of catching (or spreading) a cold, people should wash their hands frequently and cover their mouths with a tissue when coughing or sneezing. Avoiding touching the eyes or nose as much as possible, regularly cleaning bathroom and kitchen surfaces to get rid of germs, and avoiding close or extended contact with anyone who has a cold are also helpful.

Researchers have explored the idea of a cold vaccine, but many different viruses can cause colds, making the development of a single, effective vaccine a great challenge.

See also Bronchiolitis and Infectious Bronchitis • Coxsackievirus and Other Enteroviruses • Croup • Ear Infections (Otitis) • Fever • Influenza • Laryngitis • Pneumonia • Sinusitis • Sore Throat/Strep Throat • Viral Infections

* respiratory tract includes the nose, mouth, throat, and lungs. It is the pathway through which air and gases are transported down into the lungs and back out of the body.

* viruses (VY-rus-sez) are tiny infectious agents that can cause infectious diseases. Viruses can reproduce only within the cells they infect.

* immunity (ih-MYOON-uh-tee) is the condition of being protected against an infectious disease. Immunity often develops after a germ has entered the body. One type of immunity occurs when the body makes special protein molecules called antibodies to fight the disease-causing germ. The next time that germ enters the body, the antibodies quickly attack it, usually preventing the germ from causing disease.

* mucus (MYOO-kus) is a thick slippery substance that lines the interior of many body parts.

* cultures (KUL-churz) are tests in which a sample of fluid or tissue from the body is placed in a dish containing material that supports the growth of certain organisms. Typically, within days the organisms will grow and can be identified.

* acetaminophen (uh-see-tehMIH-noh-fen) is a medication commonly used to reduce fever and relieve pain.

* eustachian tubes (yoo-STAY-she-un) are the tiny channels that allow air to flow between the middle ears and the throat.

* sinusitis (sy-nyoo-SY-tis) is an infection in the sinuses, which are hollow cavities in the facial bones surrounding the nose.

* asthma (AZ-mah) is a condition in which the airway to the lungs repeatedly become narrowed and inflamed, causing breathing difficulty.