The common cold is any of a group of highly communicable diseases of the upper respiratory passages characterized by excessive secretions from the nasal membranes. Colds are the most common of all human illnesses. Most people in the United States have from one to three colds a year. Most colds are not severe and produce minor symptoms that last only a few days. However, the symptoms and the prevention of complications often require home treatment. For this reason, common colds are the most frequent causes of absenteeism in school and industry and result in the annual loss of millions of dollars in salaries and production.
Many people erroneously believe that colds are caused by chilling or dampness. Although these factors may make a person more susceptible to catching a cold, colds are probably caused by viruses. These tiny microorganisms are usually transferred from the mouth or nose of an infected person when he sneezes or coughs contaminated material into the air. The viruses are then borne by the air to other people.
Colds are more prevalent in winter, when large groups of people, such as schoolchildren and office workers, are in close contact with one another and are made more prone to illness by bad weather. Other conditions that may increase susceptibility to colds are exhaustion, nervous fatigue, and overheating.
People with allergic disorders of the respiratory tract and those who are exposed to chemicals that irritate nasal passages may catch more colds than other people, and their illnesses may be accompanied by more severe symptoms.
The common cold may involve either all or part of the respiratory tract. The earliest symptoms are a tickling sensation in the throat, general aches, and sometimes a feeling of chilliness. As the illness progresses, the mucous membranes of the nose become inflamed and swollen and secrete a clear watery mucus. Frequently a secondary bacterial infection ensues, and the discharge becomes thick and yellow. In addition, the mucous membranes of the throat, larynx, and bronchial tubes may become infected and inflamed, producing a sore throat, hoarseness, severe coughing, and congestion. Other symptoms of colds include headache and fever. The temperature may reach 102° F. and is accompanied by severe generalized aching and loss of appetite. Colds last anywhere from three to ten days but they may last longer if complications should occur.
Complications of colds include secondary bacterial infection involving the middle ear, sinuses, throat, respiratory passages, or the lungs. Middle-ear infections may result when infected mucus is forced into the inner ear by blowing the nose too hard. Lung and throat diseases may result if the tissues have been continually irritated and weakened by coughing. Elderly people and those who are in poor health are particularly prone to cold complications.
The treatment of colds is designed to relieve symptoms and to prevent complications. Bed rest is required when the temperature exceeds 100° F., and soft nutritious foods and the increased intake of fruit juices, tea, and other liquids are advisable. Aspirin may be given to relieve pain, and cough syrups may be prescribed if coughing is severe. Nose drops and nasal sprays may be used to shrink swollen respiratory membranes and reduce nasal secretions. Antihistamines, which relieve some allergic respiratory disorders, are not particularly effective in the treatment of colds. Unless a secondary bacterial infection is involved, antibiotic drugs are not useful for colds.
Various cold prevention measures, such as large doses of vitamins, frequent exposure to sunlight, and removal of the tonsils and adenoids, have been suggested, but none has proved generally effective. However, general good health may make a person less likely to catch colds.