The common cold, also called a rhinovirus or coronavirus infection, is a viral infection of the upper respiratory system, including the nose, throat, sinuses, eustachian tubes, trachea, larynx, and bronchial tubes. Over 200 different viruses can cause a cold. Almost all colds clear up in less than two weeks without complications.
Cold season in the United States begins in early autumn and extends through early spring. Although it is not true that getting wet or being in a draft causes a cold (a person has to come in contact with the virus to catch a cold), certain conditions may lead to increased susceptibility. These include:
- fatigue and overwork
- emotional stress
- poor nutrition
- living or working in crowded conditions
Although most colds resolve on their own without complications, they are a leading cause of visits to the doctor and of time lost from work and school. Treating symptoms of the common cold has given rise in the United States to a multi-million dollar industry in over-the-counter medications.
Colds make the upper respiratory system less resistant to bacterial infection. Secondary bacterial infection may lead to middle ear infection ( otitis media), bronchitis, pneumonia , sinus infection, or strep throat . People with chronic lung disease, asthma , diabetes, or a weakened immune system are more likely to develop these complications.
People with colds are contagious during the first two to four days of the infection. Colds pass from person to person in several ways. When an infected person coughs, sneezes, or speaks, tiny fluid droplets containing the virus are expelled. If these are breathed in by other people, the virus may establish itself in their noses and airways.
Colds may also be passed through direct contact. If a person with a cold touches his runny nose or watery eyes, then shakes hands with another person, some of the virus is transferred to the uninfected person. If that person then touches his mouth, nose, or eyes, the virus is transferred to an environment where it can reproduce and cause a cold.
In addition, cold viruses can be spread through inanimate objects (door knobs, telephones, toys ) that become contaminated with the virus. This is a common method of transmission in childcare centers. If a child with a cold touches his runny nose, then plays with a toy, some of the virus may be transferred to the toy. When another child plays with the toy a short time later, he may pick up some of the virus on his hands. The second child then touches his contaminated hands to his eyes, nose, or mouth and transfers some of the cold virus to himself.
Colds are the most common illness to strike any part of the body, with over one billion colds in the United States each year. Anyone can get a cold, although pre-school and grade school children catch them more frequently than adolescents and adults. Children average six to ten colds a year. In families with children in school, the number can be as high as 12 per year. Women, especially those aged 20 to 30 years old, have more colds than men, possibly because of their closer contact with children. Individuals older than 60 usually have fewer than one cold per year. Repeated exposure to viruses causing colds creates partial immunity.
Causes and symptoms
Colds are caused by more than 200 different viruses. The most common groups are rhinoviruses and coronaviruses. Different groups of viruses are more infectious at different seasons of the year, but knowing the exact virus causing the cold is not important in treatment.
Once acquired, the cold virus attaches itself to the lining of the nasal passages and sinuses. This condition causes the infected cells to release a chemical called histamine. Histamine increases the blood flow to the infected cells, causing swelling, congestion, and increased mucus production. Within one to three days the infected person begins to show cold symptoms.
The first cold symptoms are a tickle in the throat, runny nose, and sneezing. The initial discharge from the nose is clear and thin. Later it changes to a thick yellow or greenish discharge. Most adults do not develop a fever when they catch a cold. Young children may develop a low fever of up to 102°F (38.9°C).
In addition to a runny nose and fever, signs of a cold include coughing, sneezing, nasal congestion, headache , muscle ache, chills, sore throat , hoarseness, watery eyes, tiredness, and lack of appetite. The cough that accompanies a cold is usually intermittent and dry.
Most people begin to feel better four to five days after their cold symptoms become noticeable. All symptoms are generally gone within ten days, except for a dry cough that may linger for up to three weeks.
When to call the doctor
Colds make people more susceptible to bacterial infections such as strep throat, middle ear infections, and sinus infections. People who have colds that do not begin to improve within a week or who experience chest pain , fever for more than a few days, difficulty breathing, bluish lips or fingernails, a cough that brings up greenish-yellow or grayish sputum, skin rash, swollen glands, or whitish spots on the tonsils or throat should consult a doctor to see to determine if they have acquired a secondary bacterial infection that needs to be treated with an antibiotic.
Children who have chronic lung disease, diabetes, or a weakened immune system—either from diseases such as AIDS or leukemia or as the result of medications, (corticosteroids, chemotherapy drugs)—should consult their doctor if they get a cold. Children with these health problems are more likely to get a secondary infection. For children with asthma, colds are a common trigger of asthma symptoms.
Colds are diagnosed by observing a child's symptoms. There are no laboratory tests as of 2004 for detecting the cold virus. However, a doctor may do a throat culture or blood test to rule out a secondary infection.
Influenza is sometimes confused with a cold, but flu causes much more severe symptoms, as well as a fever. Allergies to molds or pollens also can make the nose run. Allergies are usually more persistent than the common cold. An allergist can do tests to determine if the cold-like symptoms are being caused by an allergic reaction. Also, some people get a runny nose when they go outside in winter and breathe cold air. This type of runny nose is not a symptom of a cold.
There are no medicines that will cure the common cold. Given time, the body's immune system makes antibodies to fight the infection, and the cold is resolved without any intervention. Antibiotics are useless against a cold. However, there are many products that have been developed by pharmaceutical companies in the United States designed to relieve cold symptoms. These products usually contain antihistamines, decongestants , and/or pain relievers.
Antihistamines block the action of the chemical histamine that is produced when the cold virus invades the cells lining the nasal passages. Histamine increases blood flow and causes the cells to swell. Antihistamines are taken to relieve the symptoms of sneezing, runny nose, itchy eyes, and congestion. Side effects are dry mouth and drowsiness, especially with the first few doses. Antihistamines should not be taken by people who are driving or operating dangerous equipment. Some people have allergic reactions to antihistamines. Common over-the-counter antihistamines are Chlor-Trimeton, Dimetapp, Tavist, and Actifed. The generic name for two common antihistamines are chlorpheniramine and diphenhydramine.
Decongestants work to constrict the blood flow to the vessels in the nose. They can shrink the tissue, reduce congestion, and open inflamed nasal passages, making breathing easier. Decongestants can make people feel jittery or keep them from sleeping. They should not be used by people with heart disease, high blood pressure, or glaucoma. Some common decongestants are Neo-Synepherine, Novafed, and Sudafed. The generic names of common decongestants include phenylephrine, phenylpropanolamine, pseudoephedrine, and in nasal sprays naphazoline, oxymetazoline, and xylometazoline.
Many over-the-counter medications are combinations of both antihistamines and decongestants; an ache and pain reliever, such as acetaminophen (Datril, Tylenol, Panadol) or ibuprofen (Advil, Nuprin, Motrin, Medipren); and a cough suppressant (dextromethorphan). Common combination medications include Tylenol Cold and Flu, Triaminic, Sudafed Plus, and Tavist D. Aspirin should not be given to children with a cold because of its association with a risk of Reye's syndrome .
Nasal sprays and nose drops are other products promoted for reducing nasal congestion. These usually contain a decongestant, but the decongestant in the nasal preparations can act more quickly and strongly than ones found in pills or liquids because it is applied directly in the nose. Congestion returns after a few hours. People can become dependent on nasal sprays and nose drops. If used for a long time, users may suffer withdrawal symptoms when these products are discontinued. The label on the preparation should be checked for recommendations on length and frequency of use, since nasal sprays and nose drops should not be used for more than a few days.
People react differently to different cold medications and may find some more helpful than others. A medication may be effective initially then lose some of its effectiveness. Children sometimes react differently than adults. Over-the-counter cold remedies should not be given to infants without consulting a doctor first.
Care should be taken not to exceed the recommended dosages, especially when combination medications or nasal sprays are taken. These medicines do not shorten or cure a cold; at best they can only help a person feel more comfortable.
In addition to the optional use of over-the-counter cold remedies, there are some self-care steps that can be taken to ease discomfort. These include:
- drinking plenty of fluids, but avoiding acidic juices, which may irritate the throat
- gargling with warm salt water—made by adding one teaspoon of salt to 8 oz of water—for a sore throat
- avoiding second-hand smoke
- getting plenty of rest
- using a cool-mist room humidifier to ease congestion and sore throat
- rubbing Vaseline or other lubricant under the nose to prevent irritation from frequent nose blowing
- for babies too young to blow their noses, the mucus should be suctioned gently with an infant nasal aspirator (It may be necessary to soften the mucus first with a few drops of salt water.)
Alternative practitioners emphasize that people get colds because their immune systems are weak. They point out that everyone is exposed to cold viruses, but not everyone gets every cold. The difference seems to be in the ability of the immune system to fight infection. Prevention focuses on strengthening the immune system by eating a healthy diet low in sugars and high in fresh fruits and vegetables, practicing meditation or using other means to reduce stress, and getting regular moderate exercise .
Once cold symptoms appear, some naturopathic practitioners believe the symptoms should be allowed to run their course without interference. Others suggest the following:
- Aromatherapy remedy: Inhaling a steaming mixture of lemon oil, thyme oil, eucalyptus, and tea tree oil ( Melaleuca spp.).
Ayurvedic medicinal remedy: Gargling with a mixture of water, salt, and
turmeric powder or astringents, such
- Herbal remedies: Taking coneflower ( Echinacea spp.) or goldenseal ( Hydrastis canadensis ). Other useful herbs to reduce symptoms are yarrow ( Achillea millefolium ), eyebright ( Euphrasia officinalis ), garlic ( Allium sativum ), and onions ( Allium cepa ).
- Homeopathic remedies: Microdoses of Viscue album, Natrum muriaticum, Allium cepa , or Nux vomica .
- Chinese traditional medicinal remedies: Taking yin chiao (sometimes transliterated as yinquiao) tablets that contain honeysuckle and forsythia when symptoms appear as well as using natural herb loquat syrup for cough and sinus congestion.
- Nutritional therapy: The use of zinc lozenges every two hours along with high doses of vitamin C as well as eliminating dairy products for the duration of the cold.
Given time, the body produces antibodies to cure itself of a cold. Most colds last a week to ten days. Most people start feeling better within four or five days. Occasionally a cold will lead to a secondary bacterial infection that causes strep throat, bronchitis, pneumonia, sinus infection, or a middle ear infection. These conditions usually clear up rapidly when treated with an antibiotic.
It is not possible to prevent colds because the viruses that cause colds are common and highly infectious. However, there are some steps individuals can take to reduce their spread. These include:
- washing hands well and frequently, especially after touching the nose or before handling food
- using instant hand sanitizers, which are antiseptics and not antibiotics
- covering the mouth and nose when sneezing
- disposing of used tissues properly
- avoiding close contact with someone who has a cold during the first two to four days of their infection
- not sharing food, eating utensils, or cups
- using paper towels rather than shared cloth towels
- avoiding crowded places where cold germs can spread
- eating a healthy diet and getting adequate sleep
- using a daycare facility with six or fewer children, to dramatically reduce germ contact
The over-use of antibiotics has led to the development of antibiotic-resistant stains of bacteria. For these bacteria, antibiotics may be ineffective. Therefore, parents should not press the doctor to prescribe antibiotics when their children only have a cold.
Also, a parent should not give a child aspirin during a cold, because aspirin has been linked to the development of Reye's syndrome in children recovering from viral illnesses, especially influenza (flu) or chickenpox . Reye's syndrome can lead to permanent brain damage or death.
Bronchial tubes —The major airways to the lungs and their main branches.
Coronavirus —A genus of viruses that cause respiratory diseases and gastroenteritis.
Corticosteroids —A group of hormones produced naturally by the adrenal gland or manufactured synthetically. They are often used to treat inflammation. Examples include cortisone and prednisone.
Eustachian tube —A thin tube between the middle ear and the pharnyx. Its purpose is to equalize pressure on either side of the ear drum.
Reye's syndrome —A serious, life-threatening illness in children, usually developing after a bout of flu or chickenpox, and often associated with the use of aspirin. Symptoms include uncontrollable vomiting, often with lethargy, memory loss, disorientation, or delirium. Swelling of the brain may cause seizures, coma, and in severe cases, death.
Rhinovirus —A group of small RNA viruses that infects the upper respiratory system and causes the common cold.
Royston, Angela. Colds (It's Catching) Oxford, UK: Heinemann Library, 2001.
Silverstein, Alvin. Common Colds. Minneapolis, MN: Sagebrush Corp., 2001.
Judith Sims Tish Davidson, A.M.