COMMON COLD OVERVIEW

The common cold is one of the most frequent illnesses in the United States. Although most cold are mild and resolve within a short time period, colds cost billions of dollars per year, mostly due to lost time at work and school.

This article discusses the common cold in adults. Colds in children are discussed separately. (See "Patient information: The common cold in children".)

COMMON COLD CAUSES

The common cold is a group of symptoms caused by one of a large number of viruses. Rhinoviruses cause the greatest number of colds; there are more than 100 different varieties of rhinovirus. Most viruses cause a person to be ill only once. However, due to the large number of viruses, a person can have a cold multiple times through their life. The average adult experiences two to three colds per year, while children average 8 to 12 colds per year. (See "Patient information: The common cold in children".)

Colds are transmitted from person-to-person, usually by direct contact. Less often, the virus can be transmitted by touching a surface.

Direct contact — People with colds typically carry the cold virus on their hands. The virus may remain alive on the skin and capable of infecting another person for at least two hours. Thus, if a sick person shakes someone's hand and that individual then touches their eye, nose, or mouth, the virus can be transmitted and later infect that person.

Infection from particles on surfaces — Some cold viruses can live on surfaces (such as a counter top, door handle, or phone) for several hours. Studies have shown that touching surfaces contaminated with a cold virus can transmit the virus if the person touching these surfaces then touches their eye, nose, or mouth.

Inhaling viral particles — Droplets containing viral particles can be breathed, coughed, or sneezed into the air by a person with a cold. The virus can be transmitted to others if another person is standing close (a few feet) and the droplet touches their eye, nose, or mouth. Covering the mouth while coughing or sneezing greatly reduces this risk. (See 'Prevention' below.)

Most cold viruses are not spread by saliva. Thus, kissing itself is not likely to transmit the common cold, but close direct contact can. Colds are not caused by cold climates or being exposed to cold air. However, some types of virus cause more colds during certain seasons (eg, fall and winter versus spring).

COMMON COLD SIGNS AND SYMPTOMS

The common cold usually causes nasal congestion, runny nose, and sneezing. A sore throat may be present on the first day but usually resolves quickly. If a cough occurs, it generally develops on about the fourth or fifth day of symptoms, typically when congestion and runny nose are usually resolving. (See "Patient information: Sore throat in adults".)

COMMON COLD COMPLICATIONS

In most cases, colds do not cause serious illness. Most colds last for three to seven days, although many people continue to have symptoms (coughing, sneezing, congestion) for up to two weeks.

Some viruses that cause the common cold can also depress the immune system or cause swelling in the lining of the nose or airways; this can, in turn, lead to a new viral infection or bacterial infection.

• One of the more common complications is sinusitis, which is usually caused by viruses and rarely (about 2 percent of the time) by bacteria. However, it can be difficult to distinguish bacterial sinusitis from sinusitis caused by a cold because the signs and symptoms can be similar (table 1). Having thick or yellow to green-colored nasal discharge does not mean that bacterial sinusitis has developed; discolored nasal discharge is a normal phase of the common cold. (See "Patient information: Acute sinusitis (sinus infection)".)
• Lower respiratory infections, such as pneumonia or bronchitis, may develop following a cold. (See "Patient information: Acute bronchitis in adults" and "Patient information: Pneumonia in adults".)
• Infection of the middle ear, or otitis media, can accompany or follow a cold. (See "Patient information: Ear infections (otitis media) in children".)
• The influenza virus, which causes the flu, can also cause features similar to those of a cold (table 2). However, the flu usually causes other signs and symptoms (fever, body aches) and is more serious than a cold. (See "Patient information: Influenza symptoms and treatment".)

COMMON COLD TREATMENT

There is no specific treatment for the viruses that cause the common cold. Most treatments are aimed at relieving some of the symptoms of the cold, but do not shorten or cure the cold. Antibiotics are not useful for treating the common cold; antibiotics are only used to treat illnesses caused by bacteria, not viruses.

The symptoms of a cold will resolve over time, even without any treatment. However, the symptoms can last for several weeks; a person with a cold can have morning coughing and nasal congestion or runny nose for up to two weeks after symptoms first develop.

The following are treatments that may reduce the symptoms caused by the common cold. People with underlying medical conditions and those who use other over-the-counter or prescription medications should speak with their healthcare provider or pharmacist to ensure that it is safe to use these treatments.

Runny nose and nasal congestion — Runny nose and congestion may improve with the use of decongestants. Pseudoephedrine is a decongestant that can improve nasal congestion. Most drugstores in the United States carry pseudoephedrine behind the counter, so it must be requested from the pharmacist (a prescription is not required).

Antihistamines such as diphenhydramine (Benadryl®) may also help, but can cause side effects such as drowsiness and drying of the eyes, nose, and mouth.

Nasal inhalers, including ipratropium bromide (Atrovent®, available by prescription) may relieve runny nose and sneezing while cromolyn sodium (NasalCrom®, a non-prescription medicine) may relieve runny nose, cough, and sneezing.

Other nasal sprays such a oxymetazoline (Afrin® and others) can also give temporary relief of nasal congestion. However, these sprays should never be used for more than two to three days; use for more than three days use can worsen congestion. (See "Patient information: Nonallergic rhinitis (runny or stuffy nose)", in the section on rhinitis medicamentosa).

Sore throat and headache — Sore throat and headache are best treated with a mild pain reliever such as acetaminophen (Tylenol®) or a non-steroidal anti-inflammatory agent such as ibuprofen or naproxen (Motrin® or Aleve®). Recommended doses of these treatments are provided here (table 3).

Cough — Common cough medicine ingredients include guaifenesin and dextromethorphan; these are often combined with other medications in over-the-counter cold formulas. However, the benefit of cough medicines is likely to be small to non-existent. In clinical trials, cough suppressants were no more effective in reducing the duration or severity of coughing due to cold than a placebo (a non-drug substitute).

Antibiotics — Antibiotics should not be used to treat an uncomplicated common cold. As noted above, colds are caused by viruses. Antibiotics treat bacterial, not viral infections.

Alternative treatments — Heated, humidified air can improve symptoms of nasal congestion and runny nose, and causes few to no side effects.

A number of alternative products, including vitamin C, and herbal products such as echinacea, are advertised to treat or prevent the common cold. While none of these treatments is likely to cause harm, none has been proven to be effective in clinical trials; their use is not recommended. Certain products, such as nasal gels that contain zinc (eg, Zicam®), have been associated with a permanent loss of smell.

PREVENTION

Hand washing is an essential and highly effective way to prevent the spread of infection. Hands should be wet with water and plain soap, and rubbed together for 15 to 30 seconds. Special attention should be paid to the fingernails, between the fingers, and the wrists. Hands should be rinsed thoroughly, and dried with a single use towel.

Alcohol-based hand rubs are a good alternative for disinfecting hands if a sink is not available. Hand rubs should be spread over the entire surface of hands, fingers, and wrists until dry, and may be used several times. These rubs can be used repeatedly without skin irritation or loss of effectiveness. Hand rubs are available as a liquid or wipe in small, portable sizes that are easy to carry in a pocket or handbag. When a sink is available, visibly soiled hands should be washed with soap and water.

Hands should be washed before preparing food and eating, and after coughing, blowing the nose, or sneezing. While it is not always possible to limit contact with people who may be infected with a cold, touching the eyes, nose, or mouth after direct contact should be avoided when possible.

In addition, tissues should be used to cover the mouth when sneezing or coughing. These used tissues should be disposed of promptly. Sneezing/coughing into the sleeve of one's clothing (at the inner elbow) is another means of containing sprays of saliva and secretions and does not contaminate the hands.

SUMMARY

• The average adult experiences two to three colds per year, while children average 8 to 12 colds per year.
• Symptoms of the common cold usually include nasal congestion, runny nose, and sneezing. They typically last for three to seven days, although many people have symptoms (coughing, sneezing, congestion) for up to two weeks.
• People with colds typically carry the cold virus on their hands, where it can infect another person for at least two hours. Some cold viruses can live on surfaces (such as a counter top, door handle, or phone) for several hours. Droplets containing viral particles can be breathed, coughed, or sneezed into the air.
• There is no specific treatment for colds. Treatment may reduce some of the symptoms of the cold, but do not shorten or cure the cold. Antibiotics are not useful for treating the common cold.
• Hand washing can prevent the spread of infection. Hands should be wet with water and plain soap, and rubbed together for 15 to 30 seconds. Alcohol-based hand rubs are a good alternative for disinfecting hands if a sink is not available.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed every four months on our web site (www.uptodate.com/patients).

Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information

Patient information: The common cold in children
Patient information: Sore throat in adults
Patient information: Acute sinusitis (sinus infection)
Patient information: Acute bronchitis in adults
Patient information: Pneumonia in adults
Patient information: Ear infections (otitis media) in children
Patient information: Influenza symptoms and treatment
Patient information: Nonallergic rhinitis (runny or stuffy nose)

Professional level information

Acute bronchitis in adults
Clinical use of echinacea
Coronaviruses
Diagnosis of allergic rhinitis (rhinosinusitis)
Epidemiology, clinical manifestations, and pathogenesis of rhinovirus infections
The common cold in adults: Diagnosis and clinical features
The common cold in adults: Treatment and prevention

The following organizations also provide reliable health information.

• National Library of Medicine

      (www.nlm.nih.gov/medlineplus/commoncold.html, available in Spanish)

• National Institute of Allergy and Infectious Diseases

      (www3.niaid.nih.gov/topics/commonCold/)

• American Lung Association

      (http://www.lungusa.org/lung-disease/influenza/in-depth-resources/cold-and-flu-guidelines.html)

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