The common cold is a viral infection of the upper respiratory system, which includes the nose, throat, sinuses, eustachian tubes, trachea, larynx, and bronchial tubes. Although more than 200 different viruses can cause a cold, 30–50% are caused by a group known as rhinoviruses. Almost all colds clear up in less than two weeks without complications.
Colds, sometimes called rhinovirus or coronavirus infections, are the most common illness to strike any part of the body. It is estimated that the average person has more than 50 colds during a lifetime. Anyone can get a cold, although preschool and grade school children catch them more frequently than adolescents and adults. Repeated exposure to viruses causing colds creates partial immunity.
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 to a multimillion dollar industry in over-the-counter medications, yet none of these medications are actually anti-viral to the rhinovirus.
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
- inadequate rest or sleep
- living or working in crowded conditions
Colds make the upper respiratory system less resistant to secondary bacterial infection. Secondary bacterial infection may lead to a number of other complications, including middle ear infection, 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.
Causes & symptoms
Colds are caused by more than 200 different viruses. The most common groups include 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.
People with colds are contagious during the first two to four days of the onset of symptoms. 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. For example, 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.
Finally, 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 child care centers. Another vector of transmission is air travel, due to closed air circulation in buildings.
Once acquired, the cold virus attaches itself to the lining of the nasal passages and sinuses. This 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 usually a tickle in the throat, runny nose, and sneezing. The initial discharge from the nose is clear and thin. Later, it may change 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).
Other symptoms of a cold include coughing, sneezing, nasal congestion, headache, muscle ache, chills, sore throat, hoarseness, watery eyes, fatigue, dull hearing and blocked eustachian tube (a danger when flying), 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 10 days, except for a dry cough that may linger for up to three weeks.
Colds make people more susceptible to secondary bacterial infections such as strep throat, middle ear infections, and sinus infections. A person should seek a doctor's consultation if the cold does not begin to improve within a week. If an individual experiences 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, then that person should also consult a doctor to see if they have acquired a secondary bacterial infection that needs to be treated with an antibiotic.
People who have emphysema, 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. People with these health problems are more likely to get a secondary infection.
Colds are diagnosed by observing a person's symptoms and symptom history. There are no laboratory tests readily available to detect the cold virus. However, a doctor may do a throat or nasal culture, or blood test to rule out a secondary infection.
Influenza is sometimes confused with a cold, but the flu causes much more severe symptoms, and is generally accompanied by a fever. Allergies to molds or pollens also can cause a runny nose and eyes. Allergies are usually more persistent than the common cold. An allergist
or a physician 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 out-side in winter and breathe cold air. This type of runny nose, however, is not a symptom of a cold.
The patient should drink plenty of fluids and eat nutritious foods. In fact, the old adage, "Feed a cold, starve a fever" was scientifically proven true in 2002. Dutch scientists found that cold-fighting immune responses rose after consuming a full meal while fasting increased those that combat most fevers. Chicken soup with ginger, scallions, and rice noodles is nutritious and has properties that help the patient to recover. Rest, to allow the body to fight infection, is very important. Gargling with saltwater (half teaspoon salt in one cup of water) helps to soothe a sore throat. A vaporizer also will make the patient feel more comfortable. Rubbing petroleum jelly or some other lubricant under the nose will prevent irritation from frequent nose blowing. For babies, nasal 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.
Herbals can be taken to stimulate the immune system, for antiviral activity, and to relieve symptoms. The following herbs are used to treat colds:
- Ginger (Zingiber officinale) reduces fever and pain, has a sedative effect, settles the stomach, and suppresses cough.
- Forsythia (Forsythia suspensa) fruit can be taken as a tea for its anti-inflammatory, fever reducing, and antimicrobial properties.
- Honeysuckle (Lonicera japonica) flower can be taken as a tea for its anti-inflammatory, fever reducing, and antimicrobial properties.
- Aniseed (Pimpinella anisum) can be added to tea to expel phlegm, induce sweating, ease nausea, and ease stomach gas.
- Slippery elm powdered bark (Ulmus fulva) can be taken as a tea or slurry or capsules to soothe sore throat, to ease cough, and to thin mucous.
- Echinacea (Echinacea purpurea or augustifolia) relieved cold symptoms in clinical studies. The usual dosage is 500 mg of crude powdered root or plant thrice on the first day, then 250 mg four times daily thereafter. This may also be taken as a tincture.
- Goldenseal (Hydrastis canadensis) has fever reducing, antibacterial, anti-inflammatory, and antitussive properties. The usual dose is 125 mg three to four times daily. Goldenseal should not be taken for more than one week. Goldenseal may also be prepared as a tincture.
- Astragalus (Astragalus membranaceus) boosts the immune system and improves the body's response to stress. The common dose is 250 mg of extract four times daily.
- Cordyceps (Cordyceps sinensis) modulates and boosts the immune system and improves respiration. The usual dose is 500 mg two to three times daily.
- Elder (Sambucus) has antiviral activity, increases sweating, decreases inflammation, and decreases nasal discharge. The usual dose is 500 mg of extract thrice daily.
- Stinging nettle (Urtica dioica) has antihistamine and anti-inflammatory properties. The common dose is 300 mg four times daily.
- Schisandra (Schisandra chinensis) helps the body fight disease and increases endurance.
- Grape (Vitis vinifera) seed extract has antihistamine and anti-inflammatory properties. The usual dose is 50 mg three times daily.
- Eucalyptus (Eucalyptus globulus) or peppermint (Mentha piperita) essential oils added to a steam vaporizer may help clear chest and nasal congestion and disinfect room air.
- Boneset infusion (Eupatroium perfoliatum) relieves aches and fever.
- Yarrow (Achillea millefolium) is a diaphoretic.
- Supplemental larch from the inner bark of the western larch tree has been shown in some clinical trials to fight persistent colds and ear aches.
Chinese herbal treatments are based on the specific symptoms of colds and include a variety of Radix, Rhizoma, Semen, and Herba species. Chinese patent medicines for cold include:
- Wu Shi Cha (Noon tea): once or twice daily.
- Yin Qiao Jie Du Pian (Honeysuckle and Forsythia Tablet to Overcome Toxins): four to six, twice daily.
- Sang Ju Gan Mao (Mulberry Leaf and Chrysanthemum to Treat Common Cold): one packet of infusion or four to eight tablets, twice or thrice daily.
- Ling Yang Gan Mao Pian (Atelopis Tablet for Common Cold): four to six, twice daily.
- Ban Lan Gen Chong Ji (Isatidis Infusion): one packet twice or thrice daily.
- Huo Xiang Zheng Qi (Agastache to Rectify Qi): 6 g or four to six tablets.
The effectiveness of zinc lozenges for preventing or treating the common cold is controversial. Numerous studies have generated contradicting results. It has been suggested that the citric acid, sorbitol, or mannitol in some lozenges may bind zinc and reduce effectiveness, hence the varying results of these studies. The recommended dosage is to suck on one lozenge every two hours while awake beginning at the first cold symptoms. Side effects are bad taste, nausea, and vomiting.
Ayurvedic medicine practitioners recommend gargling with a mixture of water, salt, and turmeric powder or astringents such as alum, sumac, sage, and bayberry to ease a sore throat.
Homeopaths recommend microdoses of Viscue album, Natrum muriaticum, Allium cepa, or Nux vomica.
There are no known medicines proven to shorten or cure the common cold. Antibiotics are useless against a cold, and can enhance bacterial resistance, if used carelessly. Nonprescription products to relieve cold symptoms usually contain antihistamines, decongestants, and/or pain relievers. 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. Aspirin should not be given to children with a cold because of its association with a risk of Reye's syndrome, a serious disease.
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. Some people have allergic reactions to antihistamines. Common over-the-counter antihistamines include Chlor-Trimeton, Dimetapp, Tavist, and Actifed. The generic name for two common antihistamines are chlorpheniramine and diphenhydramine.
Decongestants 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. Nasal sprays and nose drop decongestants can act more quickly and strongly than ones found in pills or liquids because they are applied directly in the nose. Congestion returns after a few hours. Persons can become dependent on nasal sprays and nose drops, so they should not be used for more than a few days.
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.
Given time, the body will make antibodies to cure itself of a cold. Most colds last seven to 10 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.
Prevention focuses on strengthening the immune system by eating a healthy diet low in sugars and high in fresh fruits and vegetables, practicing meditation to reduce stress, getting adequate sleep, and getting regular moderate exercise. Some steps persons can take to prevent catching a cold and to reduce their spread include:
- washing hands well and frequently
- covering the mouth and nose when sneezing
- 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
- avoiding crowded places where cold viruses can spread
- keeping hands away from the face
- avoiding cigarette smoke
- taking Echinacea; 250 mg up to four times daily for three weeks on, one week off
- taking astragalus; 250 mg to 500 mg daily.
- taking a multivitamin with zinc
- taking vitamin C ; 500 mg
- taking Anas barbariae hepatis; one dose weekly
In 2002, researchers discovered that transmission of the rhinovirus may be prevented through the use of anti-septic skin cleansers containing salicylic acid or pyroglutamic acid. The cleansers have properties that can kill the viruses and help prevent hand-to-hand transmission, but further research on their effectiveness remains to be done.
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