What Is It?

The common cold, also called viral rhinitis, is one of the most common infectious diseases in humans. Although the infection is usually mild and improves without treatment, it causes widespread illness and discomfort, resulting 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 one to three colds per year.

The common cold is an upper respiratory infection that is caused by a wide variety of viruses. More than 200 viruses that can cause the common cold have been identified. The biggest offender, called the rhinovirus, which causes up to 40 percent of colds, has 100 distinct types. Other important upper respiratory viruses include coronaviruses, adenovirus and respiratory syncytial virus. This incredible diversity has made the development of a vaccine for the common cold almost impossible.

Rhinoviruses, the most likely agents to cause colds, have a well-established seasonal pattern, peaking in the early fall and spring. Other viruses tend to cause winter colds, which are usually more debilitating. Despite popular belief, cold temperatures do not appear to increase either the incidence or severity of the common cold. There is no evidence that exposure to cold or rainy weather makes you more likely to catch a cold.

The common cold causes a group of symptoms that usually are easily recognized by patients and doctors. About 50 percent 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 rapidly by the most common symptoms of the common cold — congested nasal and sinus passages, a runny nose and sneezing. Hoarseness and cough are less likely to occur, but they may last longer than other symptoms, sometimes for several weeks. However, high fevers and chills rarely occur.

Most patients diagnose the common cold by the typical symptoms of runny nose, congestion and sneezing, and rarely consult medical attention. High fevers, severe sinus pain, shortness of breath and new wheezing 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 one 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 persist. Up to 25 percent of people may have persistent symptoms, such as a nagging cough that can last for several weeks. A small number of people may develop another illness, such as bacterial infections of the middle ear or the sinuses, and others may develop chronic bronchitis or worsening of asthma. These patients may have a prolonged illness.

Colds most often are spread to people in close contact. 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.

The common cold most often is transmitted by direct contact with the respiratory secretions of someone who is infected, usually by hand-to-hand contact. The infected respiratory secretions are passed from one person’s hand to another. The second person then touches his or her eyes or rubs his or her nose, spreading the virus there, where it can cross the delicate membranes and cause infection. It is also 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. Viruses can survive on such surfaces for up to three hours.

Therefore, to avoid being infected, it is extremely important to clean your hands frequently, carefully dispose of all used tissues and avoid rubbing your eyes and nose. These viruses also can be spread by inhaling particles from the air after an infected person has coughed or sneezed. 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. It’s important to 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, and over-the-counter cold remedies, including decongestants and cough suppressants, will help to relieve congestion and cough. Antihistamines may improve the symptoms of runny nose and watery eyes, but they should be used with care because over-the-counter formulations cause sedation. It is important to keep in mind that antibiotics do not cure the common cold, nor do they shorten the length of time that symptoms last. Vitamin C, zinc 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 data have demonstrated that this is the case.

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, severe pain over your sinuses, severe 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 usually causes a mild, self-limited 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 patients may develop bacterial infections of the ear, sinuses or lungs following the common cold.

Diseases and Conditions Center

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.