Many different viruses cause colds.
Usually, colds are spread when a person's hands come in contact with nasal secretions from an infected person.
Colds often start with a scratchy or sore throat or discomfort in the nose, followed by sneezing, a runny nose, a cough, and a general feeling of illness.
Doctors base the diagnosis on symptoms.
Good hygiene, including frequent hand washing, is the best way to prevent colds.
Rest, decongestants, acetaminophen, and nonsteroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen) can help relieve symptoms.
Common colds are among the most common illnesses. Many different viruses (rhinoviruses, adenoviruses, coronaviruses, and human metapneumoviruses) cause colds, but rhinoviruses (of which there are more than 100 subtypes) cause most colds. Colds caused by rhinoviruses occur more commonly in the spring and fall. Other viruses cause common coldlike illnesses at other times of the year.
Colds spread mainly when people’s hands come in contact with nasal secretions from an infected person. These secretions contain cold viruses. When people then touch their mouth, nose, or eyes, the viruses gain entry to the body and cause a cold. Less often, colds are spread when people breathe air containing droplets that were coughed or sneezed out by an infected person. A cold is most contagious during the first 1 or 2 days after symptoms develop.
Susceptibility to colds is not increased by any of the following:
Cold symptoms start 1 to 3 days after infection. Usually, the first symptom is a scratchy or sore throat or discomfort in the nose. Later, people start sneezing, have a runny nose, and feel mildly ill. Fever is not common, but a mild fever may occur at the beginning of the cold. At first, secretions from the nose are watery and clear and can be annoyingly plentiful, but eventually, they become thicker, opaque, yellow-green, and less plentiful. Many people also develop a mild cough. Symptoms usually disappear in 4 to 10 days, although the cough often lasts into the second week.
Complications may prolong the disease. Rhinovirus infection often triggers asthma attacks in people with asthma Asthma Asthma is a condition in which the airways narrow—usually reversibly—in response to certain stimuli. Coughing, wheezing, and shortness of breath that occur in response to specific triggers are... read more . Some people develop bacterial infections of the middle ear (otitis media Otitis Media (Acute) Acute otitis media is a bacterial or viral infection of the middle ear. Acute otitis media often occurs in people with a cold or allergies. The infected ear is painful. Doctors examine the eardrum... read more ) or sinuses (sinusitis Sinusitis Sinusitis is inflammation of the sinuses, most commonly caused by a viral or bacterial infection or by an allergy. Some of the most common symptoms of sinusitis are pain, tenderness, nasal congestion... read more ). These infections develop because congestion in the nose blocks the normal drainage of those areas, allowing bacteria to grow in collections of blocked secretions.
Doctors are usually able to diagnose a cold based on the typical symptoms. A high fever, severe headache, rash, difficulty breathing, or chest pain suggests that the infection is not a simple cold.
Laboratory tests are not usually needed to diagnose a cold. If complications are suspected, doctors may order blood tests and x-rays.
Because so many different viruses cause colds and because each virus changes slightly over time, an effective vaccine has not yet been developed.
The best preventive measure is practicing good hygiene. Because many cold viruses are spread through contact with the secretions of an infected person, the following measures can help:
People with cold symptoms and people in their household and workplace should wash their hands frequently.
Sneezing and coughing should be done into tissues, which should be carefully disposed of.
When possible, people with symptoms should sleep in a separate room.
People who are coughing or sneezing because of a cold should not go to work or school where they might infect others.
Cleaning shared objects and surfaces with a disinfectant can also help reduce the spread of common cold viruses.
Despite their popularity, echinacea and high-dose vitamin C (up to 2,000 milligrams per day) do not prevent colds, nor does eating citrus fruits.
People with a cold should stay warm and comfortable and should rest. They should try to avoid spreading the infection to others by staying at home. Drinking fluids and inhaling steam or mist from a vaporizer have long been suggested as a way to help to keep secretions loose and easier to expel, but they probably help only a little bit.
Currently available antiviral drugs are not effective against colds. Antibiotics do not help people with colds, even when the nose or cough produces thick or colored mucus.
Echinacea Echinacea Echinacea is a perennial wildflower containing a variety of biologically active substances. Various parts of the plant are used medicinally. (See also Overview of Dietary Supplements.) People... read more , zinc Zinc Zinc, a mineral, is required in small quantities for many metabolic processes. Dietary sources include oysters, beef, and fortified cereals. (See also Overview of Dietary Supplements.) People... read more preparations, and vitamin C Vitamin C Deficiency In developed countries, vitamin C deficiency can occur from a diet low in vitamin C, but severe deficiency (causing scurvy) is uncommon. Not eating enough fresh fruits and vegetables can cause... read more have been suggested as treatment. Some small studies have shown them to be effective. Others have shown them to be ineffective. But no well-designed, large clinical studies have confirmed their effectiveness. Even when studies did show a benefit, the benefit was small. For example, when zinc shortened the duration of cold symptoms, it was by less than 1 day. Thus, most experts do not recommend these supplements as treatment.
Several popular nonprescription (over-the-counter) remedies help relieve cold symptoms. Because they do not cure the infection, which usually resolves after a week regardless of treatments tried, doctors feel that their use is optional, depending on how bad the person feels. Several different types of drugs are used:
Decongestants, which help open clogged nasal passages
Antihistamines, which may help dry a runny nose
Nonsteroidal anti-inflammatory drugs (NSAIDs) or acetaminophen, which can relieve aches and pains and reduce fever
Cough syrups, which may make coughing easier by thinning secretions and loosening mucus (expectorants) or which may suppress cough (suppressants)
These drugs are most often sold as combinations but can also be obtained individually.
Inhaled decongestants are better than forms taken by mouth for relieving nasal congestion. However, using inhaled forms for more than 3 to 5 days, then stopping, may make congestion worse than it was originally. Ipratropium, a nasal spray available only by prescription, helps dry a runny nose.
Older antihistamines, such as chlorpheniramine, can cause drowsiness. Newer antihistamines, such as loratadine, are less likely to cause drowsiness but are ineffective for treating the common cold.
Decongestants and antihistamines should not be given to children under 4 years old.
NSAIDs, such as aspirin, ibuprofen, and naproxen, can relieve aches and pains and reduce fever, as can acetaminophen. Aspirin is generally not recommended for children because in children, it increases the risk of Reye syndrome Reye Syndrome Reye syndrome is a very rare but life-threatening disorder that causes inflammation and swelling of the brain and impairment and loss of function of the liver. The cause of Reye syndrome is... read more , which is a rare but life-threatening disorder.
Cough suppressants are not routinely recommended because coughing is a good way to clear secretions and debris from the airways during a viral infection. However, a severe cough that interferes with sleep or causes great discomfort can be treated with a cough suppressant.