The common cold, also called viral rhinitis, is one of the most common infectious diseases in humans. The infection is usually mild and improves without treatment. Because of the large number of people who get the common cold, this illness results in nearly 26 million days of missed school and 23 million days of absence from work every year in the United States. The average American has 1 to 3 colds per year.
The common cold is an upper respiratory infection that is caused by several families of viruses. Within these virus families, more than 200 specific viruses that can cause the common cold have been identified. The virus family that causes the most colds is called rhinovirus. Rhinoviruses cause up to 40% of colds, and this virus family has at least 100 distinct virus types in its group. Other important upper respiratory virus families are named coronavirus, adenovirus and respiratory syncytial virus. Since so many viruses can cause cold symptoms, development of a vaccine for the common cold has not been possible.
Rhinoviruses cause most colds in the early fall and spring. Other viruses tend to cause winter colds and their symptoms can be more debilitating. There is no evidence that going out in cold or rainy weather makes you more likely to catch a cold.
The common cold causes a group of symptoms that are easily recognized by patients and doctors. About 50% of patients will develop a sore throat, which is often the first symptom to appear because it can occur as early as 10 hours after infection. This is followed by congestion in the nose and sinuses, a runny nose and sneezing. Hoarseness and cough can also occur and may last longer than other symptoms, sometimes for several weeks. High fevers are rare with the common cold.
Most people diagnose the common cold by the typical symptoms of runny nose, congestion and sneezing. Usually it isn't necessary for you to see a health care provider. You should see a doctor if you develop a high fever, severe sinus pain, ear pain, shortness of breath or new wheezing. These are symptoms that suggest you either have something other than a cold or a complication of the cold.
Symptoms typically peak on the second, third or fourth days of infection and last about 1 week. People are most infectious (likely to pass the cold onto others) during the first 24 hours of the illness, and they usually remain infectious for as long as the symptoms last. Up to 25% of people may have persistent symptoms, such as a nagging cough that can last for several weeks. For a small number of people, the congestion from a cold may allow another illness to take hold, such as a bacterial infection of the middle ear or the sinuses. Respiratory complications such as bronchitis or asthma can cause symptoms that last for a month or longer.
The common cold most often is transmitted by direct contact with germs from the nose, mouth, or coughed or sneezed droplets from someone who is infected, usually by hand-to-hand contact. Virus particles are passed from one person's hand to another person's hand. The second person then touches his or her eyes or rubs his or her nose, spreading the virus there, where the virus can start a new infection. It is possible to become infected by touching a surface, such as a tabletop or doorknob that was recently touched by an infected person, and then touching your eyes or nose. These viruses also can be spread by inhaling particles from the air after an infected person has coughed or sneezed.
Usually about half of the family members of an infected person will become ill. Colds also are transmitted frequently in schools and day care facilities.
To avoid getting or spreading a cold, it helps to clean your hands often, carefully dispose of all used tissues, and avoid rubbing your eyes and nose. If possible, you should avoid close, prolonged exposure to people who have colds.
People who exercise regularly, especially those who exercise daily, have fewer colds per year than those who are less active.
Although medical therapies can improve the symptoms of the common cold, they do not prevent, cure or shorten the illness. Drink enough fluids, get plenty of rest and treat your symptoms to keep yourself as comfortable as possible. Gargling warm salt water can soothe a sore throat. Inhaling steam may improve nasal congestion temporarily. Over-the-counter cold remedies that contain a decongestant will help to dry secretions and relieve congestion. These remedies may also relieve cough, if the cough is triggered by mucus in the throat. Antihistamines may improve the symptoms of runny nose and watery eyes, but they should be used with care because over-the-counter versions cause sedation. Over-the-counter cough suppressants do not have a proven benefit, but some people feel that they are helpful. It is important to keep in mind that antibiotics do not cure the common cold or shorten the length of time that symptoms last. Vitamin C and echinacea (a frequently used herbal therapy) have been widely rumored to decrease the likelihood of developing the common cold and to shorten symptoms, but no conclusive research has shown that this is true. Zinc-containing products advertised to treat the common cold remain popular. Some studies suggest that zinc lozenges may shorten the duration of symptoms, but questions remain regarding the best and safest dose.
A small percentage of people who have a common cold develop bacterial infections of the middle ear, sinuses or lungs. If you develop high fevers, ear pain, a toothache, severe pain over your sinuses, wheezing or shortness of breath, you should see your physician to be sure that you don't have a more serious illness, such as pneumonia, bacterial sinusitis or a middle ear infection.
The common cold is a mild infection that improves on its own within a week. However, some people may have symptoms that last for several weeks, and a small number of people may develop bacterial infections of the ear, sinuses or lungs following the common cold.
Centers for Disease Control and Prevention (CDC)
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