Common Cold

I

Introduction

Common Cold, acute infectious disease of the upper respiratory tract, caused by more than 200 kinds of viruses. The common cold is the primary cause of absenteeism in schools and the workplace. According to the National Institutes of Health, American children have six to ten colds a year on average, while adults average two to four colds annually. Children probably have so many because they spend time in close contact in schools and daycare centers, making it easy for the virus to spread.

II

Symptoms of a Cold

Infection with a cold virus affects the mucous membranes of the nose and throat, causing such symptoms as nasal congestion and discharge, sore throat, and coughing. These symptoms are typical also of respiratory infections caused by bacteria, and of allergic conditions such as hay fever and asthma; therefore, the common cold is difficult to diagnose with certainty.

Normally a cold runs a mild course, without fever, and goes away on its own in about seven days. If the symptoms do not go away after two weeks, they may result from an allergy. The medical significance of a cold lies in the possible complications that may follow. Various diseases, such as bronchitis, pneumonia, and sinus or middle-ear infections, may arise from the cold. A cold accompanied by high fever, by a cough that brings up mucus, or by severe sinus pain may call for attention from a physician.

III

Causes and Transmission of a Cold

The great majority of colds are caused by viruses, and the rhinoviruses cause about half of all colds. Research indicates that there are several strains of each type of cold virus with varying degrees of virulence. Infection with one strain of cold virus provides only a brief immunity to reinfection by the same strain, and gives no immunity against the other viral strains.

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The common cold was once thought to result from exposure to cold weather, a belief probably traceable to the fact that people tend to crowd together indoors at this time, causing a more efficient transmission of virus from person to person. Chilling was also believed to cause a cold, but there is no scientific evidence for the belief that chills or exposure to cold play a role in causing colds. Research does suggest, however, that stress may weaken the body’s immune response and thereby make it easier to become infected.

Cold viruses are transmitted from person to person through droplets of mucus in the air. The droplets containing cold viruses enter the air when an infected person sneezes. The viruses can also be spread by hand—for example, by touching the hand of an infected person, or by touching a telephone, piece of paper, or other contaminated surface, and then touching the eyes or nose.

IV

Prevention and Treatment of Colds

No cure is known for the common cold and no preventive drug has yet been found. Various antihistamine drugs were once claimed to be effective in the prevention of colds if taken at the onset, but that view has been discredited. American chemist and Nobel laureate Linus Pauling proposed that large doses of vitamin C can prevent a cold or alleviate its symptoms, but subsequent studies have failed to substantiate his claim. There is some evidence, however, that vitamin C can shorten the duration of a cold.

Present-day methods of treating a cold are directed toward the relief of symptoms through over-the-counter preparations, especially those containing aspirin or acetaminophen. Many remedies are available that soothe symptoms but do not shorten the length of a cold. Physicians advise against giving aspirin to children and teenagers because it has been linked with a rare disease called Reye’s syndrome that can develop after a viral infection. In addition, an advisory panel to the U.S. Food and Drug Administration (FDA) recommended in 2007 that over-the-counter cold preparations be banned for children under the age of six. The panel reported that these remedies do not lessen symptoms in young children and in rare cases cause serious complications.

Physicians also advise people with colds to drink plenty of fluids. Bed rest may be recommended to avoid complications, even when the cold itself is not incapacitating. Antibiotics, which fight bacterial infections, should not be administered because nearly all colds are caused by viruses rather than by bacteria. Antibiotics may be prescribed if sinus or middle-ear infections develop; however, they are ineffective as a preventive measure.

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