- Acute viral nasopharyngitis, adenoviruses, adrenal gland, allergic rhinitis, allergy, antihistamine, benzocaine, bronchial tubes, bronchitis, cilia, coronaviruses, cortisol, coxsackieviruses, crystal meth, cytokines, dander, dyclonine, echoviruses, epithelial, eustachian tubes, Fahrenheit, flu, hay fever, hexylresorcinol, HIV, human immunodeficiency virus, humidifier, immune system, immunity, influenza, larynx, lozenges, malnutrition, menthol, methamphetamine, mucous membrane, mucus, otitis media, phenol/sodium phenolate, pneumonia, respiratory syncytial viruses (RSV), rhinoviruses, sinus, sinusitis, Strep throat, stress, symptomatic, thymus gland, trachea, turbinates, vaporizer, viral infection, viral load, virus.
- The common cold, or acute viral nasopharyngitis, is a viral infection of the upper respiratory system, which may involve the nose, throat, sinuses, eustachian tubes (connects the ears to the throat), trachea (windpipe), larynx (voice box), and bronchial tubes (airways).
- Colds are one of the leading causes of doctor visits and missed days from school and work. According to the Centers for Disease Control and Prevention (CDC), 22 million school days are lost annually in the United States as a result of the common cold. Over the course of a year, people in the United States suffer one billion colds, according to some estimates.
- Americans spend about $2.9 billion on over-the-counter (OTC) drugs in addition to $400 million on prescription medicines annually for the symptomatic relief from colds.
- It is estimated that the average person contracts more than 50 colds during a lifetime. Anyone can get a cold, although pre-school and grade school children catch them more frequently than adolescents and adults.
- One of the main reasons that colds are so common among children is because they are often in close contact with each other in daycare centers and schools. In families with children in school, the number of colds per child can be as high as twelve a year. Also, the thymus gland, which produces immune system cells, is immature in children. Subsequently they have decreased resistance to bacterial and viral infections such as colds.
- Adults average about two to four colds annually, although the range varies widely. Women, especially those aged 20-30 years, experience more colds than men, possibly due to closer contact with children. Based on studies, on average, people older than 60 have less than one cold a year.
- In the United States, most colds occur during the fall and winter. Beginning in late August or early September, the rate of colds increases slowly over a few weeks and remains high until March or April, when it declines. The seasonal variation may relate to the opening of schools and to cold weather, which prompt people to spend more time indoors and increase the chances that viruses will spread from person to person.
- Seasonal changes in relative humidity also may affect the prevalence of colds. The most common cold-causing viruses survive better when humidity is low during the colder months of the year. Cold weather also may make the inside lining of the nose drier and more vulnerable to viral infection.
Risk factors and causes
- The cause of developing a cold is due to a viral infection, including rhinoviruses, coronaviruses, adenoviruses, echoviruses, respiratory syncytial viruses (RSV), and coxsackieviruses, which can infect the upper respiratory system. Although over a hundred different viruses can cause colds, 30-50% are caused by rhinoviruses.
- The nose contains shelf-like structures called turbinates, which help trap particles (dust, dander, dirt, and viruses) entering the nasal passages. Material deposited in the nose is transported by cilia, which are hair-like structures that sweep particles to the back of the throat within 10-15 minutes of exposure. Viruses attach to receptors on epithelial (outer layer of skin) cells. In response to infection, the immune system triggers a series of events, including release of inflammatory cytokines (a group of proteins that help regulate inflammation, blood cell production, and immunity), such as interleukin-6 (IL-6), interleukin-8 (IL-8), and granulocyte-macrophage colony-stimulating factor or GMCSF), fluid leakage (runny nose), mucous membrane swelling (stuffy nose), increased mucous production, and stimulation of sneeze and cough reflexes. Nasal symptoms can begin as early as two hours after exposure, while cough and sore throat symptoms usually begin 10-12 hours following exposure to the virus. In the early stages of a cold, when the number of infecting viruses is still low, it may be possible for the body to build an effective immune response that prevents the cold from worsening. Keeping the number of viruses, called viral load, low decreases the ability of the cold virus to replicate (multiply) and cause infection.
- The most common means of infection is from direct contact with the cold virus, such as an individual touching their skin to environmental surfaces (including telephones, computer keyboards, and stair rails) that have cold germs on them and then touching the eyes or nose. If an individual is physically exhausted or overtired, the chances of becoming a victim to the cold virus increase due to a impairment in immunity, or the decreased ability of the immune system to fight off infection.
- Colds are also easily transmitted (by coughing or sneezing) by inhaling droplets of mucus contaminated with cold viruses. Mucus is a thick, slippery secretion of the inner lining or organs (called mucous membranes) in the body including the nostril, ears, anus, and lips. The cold virus is spread when the infected mucus drops come in contact with other individual's noses and eyes, occurring this way more frequently than through the mouth.
- Social activity: Individuals exposed to large amounts of people during the day are also exposed to many viruses. Children attending school or playing with other kids, traveling in airplanes or buses, and having large families increases the risk of exposure to a cold virus. Being around people that are sneezing and coughing increases the chances for getting a cold virus. Touching things that others frequently touch, such as railings and doors in public facilities, also increases the chances of developing a cold. An individual's work place may also increase their chances of exposure to a cold virus. Healthcare workers (such as nurses, pharmacists, and doctors), day care workers, people that work in retail stores, and individuals in public office are exposed to many people daily, where the chances of viral exposure and developing a cold is increased.
Children and infants (less than 14 years of age) are especially susceptible to colds. Their immune systems have not yet become adjusted to being exposed to various cold viruses and have not yet developed resistance to the viruses commonly encountered. Children also may not be as careful about cleanliness such as hand washing. Children tend to spend lots of time with other children (at play and school), making it easy for colds to spread. As they age, immunity develops for many of the common viruses that cause colds. Colds will generally occur less frequently with age.
- Seasonal changes: Both children and adults seem to be most susceptible to colds in fall and winter. In cold months when the air is very dry, people turn on their heating systems, drying the air even more. Dry air dehydrates the mucous membranes in the nose and throat, which are the first line of defense against the viruses. This allows the viruses to attack the tissue in the nose and throat. Individuals working in air conditioned offices tend to have more summer colds than people who do not work in air conditioned environments. Air conditioning dries out the air and the mucous membranes and can circulate viruses in the air.
- Environmental toxins: The risk of respiratory infections is increased by exposure to environmental toxins, including cigarette smoke, which can injure airways and damage the cilia (tiny hair-like structures that help keep the airways clear). Physically engaging in smoking or breathing in passive (second hand) smoke can damage the cilia. Toxic fumes, industrial smoke, and other air pollutants are also environmental risk factors.
- Lowered immunity: Individuals with lowered immunity, such as those with the human immunodeficiency virus (HIV) or cancer, and individuals taking certain medications such as chemotherapy, are at greater risk of developing colds. Colds can be severe in these individuals, due to poor immune status.
- Medications: Drug therapies, including corticosteroid (steroid) treatments, chemotherapy, or other medications that suppress the immune system also increase the risk of developing an infection from a cold virus.
- Stress: Stress can lower the resistance to infection by depressing the immune system Stress causes the adrenal glands to increase the production of the stress hormone called cortisol. During normal stressful circumstances, cortisol production is a healthy response of the body. Chronic (long-term) stress, however, causes the levels of cortisol to stay increased, leading to decreased immunity, hyperinsulinemia (the inability of the body to process insulin), and an increase in blood pressure. Stress during menopause may also increase the chances of catching a cold due to impaired immunity.
- Too much exercise: High-intensity or endurance exercises appear to suppress the immune system while they are being performed. Some highly trained athletes, for instance, report being susceptible to colds after strenuous exercise.
- Malnutrition: Low vitamin and mineral levels, such as vitamins A, E, C, the B vitamins, selenium, and zinc, may decrease immunity and increase the chances of getting a cold. Very low fat diets also appear to lower the immune system.
- Lack of sleep: Sleep helps the body recharge. Proper sleep (eight hours of uninterrupted sleep for an adult) can help keep the body's immune system healthy and fight off colds.
- There is no cure for the common cold. Over-the-counter (OTC) cold preparations may be used for symptoms.
- Healthcare professionals recommend seeking medical attention if a patient has a fever of 102 degrees Fahrenheit or higher, the fever is accompanied by aches, extreme fatigue, sweating, chills, and a cough with colored phlegm, or symptoms get worse instead of better or last more than 10 days. These are symptoms of a more serious viral illness such as influenza.
- With a child that has a cold, medical attention is recommended if symptoms include a fever of 102 degrees Fahrenheit or higher with chills or sweating, a fever that lasts more than 72 hours, vomiting or abdominal pain, unusual sleepiness, severe headache, difficulty breathing, persistent crying, ear pain, or a persistent cough.
- Pharmacological therapy:
- Pain relievers and fever reducers: For fever, sore throat, body aches, and headache, acetaminophen (Tylenol®) or ibuprofen (Advil®, Motrin®) may be used over-the-counter. Acetaminophen can cause liver damage, especially if taken chronically, or in doses that exceed four grams daily. Healthcare professionals recommend carefully following dosing guidelines when giving acetaminophen to children, as dosing can be confusing. Also, it is recommended to never give aspirin to children ages three to 12. Aspirin may play a role in causing Reye's syndrome, a rare but potentially fatal illness in children.
- Nasal decongestants:
Nasal decongestants are useful medications for the common cold. Nasal decongestants help dilate (open) swollen mucous membranes of the nasal passages so the individual can breathe easier. Nasal decongestants include tablets, sprays, inhalers, and nose drops. Nasal decongestants include the oral decongestant pseudoephedrine (Sudafed®), nasal sprays oxymetolazone (Afrin®) and phenylephrine (Neo-Synephrine®), and the nasal inhalers propylhexedrine (Benzedrex®) or levmetamfetamine (Vicks Vapor Inhaler®). They are safe for most patients, but they do have many side effects and conditions in which they should not be used, including in people with heart disease, high blood pressure, thyroid disease, glaucoma (increased pressure in the eyes), diabetes, seizure disorders, enlarged prostate, or by individuals using a monoamine oxidase inhibitor (MAOI, type of antidepressant). Stinging, burning, sneezing, increased nasal discharge, drying of the nostrils, and altered taste may occur. If these effects continue or become bothersome, inform a doctor. Other side effects include rapid or pounding heartbeat, dizziness, trouble sleeping, shaking of the hands, and tremors. Healthcare professionals recommend not using decongestants while pregnant or breastfeeding. If symptoms get worse, a doctor may need to evaluate the situation.
- Over time, decongestant nose drops, inhalers, and sprays can actually cause rebound congestion, which means the nasal passages are not able to function normally without using these medications. Prolonged use can also cause chronic inflammation of the mucous membranes. Decongestant nasal drops and sprays are not used for more than three days, which helps to stop the potential of nasal rebound.
- There is widespread national abuse of pseudoephedrine tablets as a drug to make methamphetamine (crystal meth or meth), an illegal drug. Methamphetamine is a highly addictive, synthetically produced central nervous system stimulant with effects similar to cocaine. Meth is the most prevalent synthetic drug manufactured in the United States and is easily produced in home laboratories using common store-bought chemicals. The ease of manufacturing meth and its highly addictive potential has caused the use of the drug to increase throughout the nation. Its use has reached epidemic levels in many parts of the country. National and state laws have attempted to stem this criminal activity by establishing limits on sales of pseudoephedrine. The pharmacist or pharmacy representative may ask for a name and address in many states to prove that the pseudoephedrine is purchased legitimately as a decongestant. There may also be limits on the how much psuedoephedrine can be purchased in one transaction as well as over a certain time period. Psuedoephedrine products may not be available in all states over-the-counter (OTC), and may need to be purchased from behind the pharmacy counter. Also, a new oral nasal decongestant formulation (Sudafed PE®) is available that decreases the potential for abuse. Sudafed PE® contains the nasal decongestant phenylephrine and not pseudoephedrine.
- Antihistamines: Antihistamines dry up excess nasal secretions (mucus), and in this way help to temporarily stop a runny nose. But they can also cause side effects such as dry mouth, constipation, and drowsiness as well as confusion and increased risk of falls if administered to elderly patients. Non-sedating antihistamines include fexofenadine (Allegra® and cetirizine (Zyrtec®.) Antihistamines that cause sedation include diphenhydramine (Benadryl®), clemastine (Tavist®), chlorpheniramine (Chlor-Trimeton®), and brompheniramine (Dimetane®.)
- Cough syrups: Nonprescription cough syrups, containing various combinations of antihistamines, decongestants, and cough suppressants, are available over-the-counter (OTC) for symptomatic relief of cough associated with a cold. Many doctors strongly discourage the use of these combination medications for any child younger than age two, in whom accidental overdoses could be fatal. Coughs associated with a cold usually last less than two to three weeks. If a cough lasts longer than three weeks, see a doctor. Cough due to colds in adults may be safely treated for as long as seven days. If the cough is productive (brings up mucus), the ingredient guaifenesin can help break up the chest congestion (water intake is also important.) If the cough is dry and hacking, a cough suppressant (dextromethorphan) can stop the cough.
- Lozenges: Sore throat caused by a cold may be self-treated if the pain is minor. Experts recommend not self-treating sore throat for more than two days. If a sore throat lasts more than seven days, healthcare professionals recommend seeing a doctor. Lozenges for sore throat contain active ingredients such as the anesthetics benzocaine, menthol, dyclonine, phenol/sodium phenolate, and hexylresorcinol. Phenol/sodium phenolate and hexylresorcinol also have antibacterial properties.
- Antiviral: A few studies have investigated the use of antiviral medications to treat rhinovirus, including interferon alfa-2a and interferon gamma. These drugs are expensive and have to be refrigerated and injected. The most common side effect of interferon alfa-2a or alfa-2b therapy is a flu-like reaction with fever, fatigue, irritability, chills, headaches, and muscle aches. These effects should become less severe and less frequent as therapy progresses.
- Pleconaril (Picovir®) is an anti-viral drug in clinical testing that targets picornaviruses, the viruses that cause the majority of common colds such as rhinoviruses. Pleconaril has been reported to be effective in an oral form, but it causes severe adverse effects including liver and kidney failure. An intranasal form with less side effects is currently under development.
- Antibiotics: Healthcare professionals do not recommend using antibiotics to treat a cold. Antibiotic resistance has been called one of the world's most pressing public health problems. It is caused by the over prescribing of antibiotics for conditions that will not respond to antibiotics, such as outer ear infections and viral infections, including colds and influenza.
- Others: Ipratropium bromide (Atrovent®), a prescription nasal spray, significantly reduced nasal drainage and sneezing in studies of naturally occurring colds.The main side effects included nasaldryness, occasional epistaxis (nosebleeds), and headache. The duration of relieffrom nasal stuffiness is thought to be over threehours. Nedocromil (Tilade®) and sodium cromoglycate (Cromolyn®) are prescription drugs used in the nose have been reported to reduce the severity of the rhinovirus upper respiratory tractinfections (a common cold).
- Non-pharmacological therapy:
- Non drug
therapy can help reduce cold symptoms and is recommended by healthcare professionals for all infants younger than nine months. Patients of all ages benefit from rest and increased intake of fluids. The American Academy of Pediatrics highly recommends the use of calibrated measuring devices for the administration of all liquid medications to children and infants.
- Saline nasal drops:Isotonic saline nasal drops are recommended for infants. Healthcare professionals recommend one to two drops in each nostril 15 to 20 minutes before feeding and bedtime and repeated ten minutes later. Adults and children may also use saline nasal drops (Ocean® nasal spray) to relieve dry and inflamed nasal passages.
- Nasal bulb aspirator: A nasal bulb aspirator may be used to gently suction mucus and aid in clearing the nasal passages in infants and young children. Nasal bulb aspirators use gentle suction to remove excess mucus from the nasal passages. They can be purchased without a prescription at pharmacies and most retail outlets.
- Elevating the head: Elevating the head of an infant's or child's bed may facilitate the drainage of secretions. Parents and caregivers should be cautioned, however, never to place pillows around or under an infant's head due to increased risk of suffocation.
- Humidification: A cool mist vaporizer will add moisture to the air, relieving symptoms such as sore throat and congestion. Hot steam humidifiers are not recommended because of the risk of scalding. Humidifiers and vaporizers must be cleaned frequently to deter growth of bacteria and other pathogens. Infants and young children also benefit from exposure to warm, steamy air, which helps to clear nasal and bronchial passages of mucus and to ease breathing, especially at night. Parents can hold the infant or child on their lap outside the shower while running a warm or hot shower to generate steam. The child should not be placed in the water.
- Petroleum jelly: Petroleum jelly may be applied on skin underneath the nose if it becomes raw from repeated wiping.
- This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
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Copyright © 2011 Natural Standard (www.naturalstandard.com)
The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.