Just about everyone gets colds—a general term referring to a group of minor but highly contagious upper respiratory viral infections that cause inflammation of the mucous linings of the nose and throat. Symptoms generally develop one to two days after exposure to the virus, and anyone with a common cold is contagious for about two to three days, starting the day before symptoms appear. There is no cure, but there are measures that alleviate symptoms during recovery, which generally takes about a week.
Scientists estimate that there are as many as 200 different cold viruses, the most common being the rhinoviruses (nose viruses), which are estimated to cause 30 percent of all colds. No one knows what makes a person susceptible to colds in general or to any particular cold. Although newborns are thought to be immune to 20 percent of rhinoviruses (they get the antibodies from their mothers), they quickly lose their immunity. Small children are the most susceptible to colds, and can have six or eight a year. People who spend a lot of time with children, such as teachers, also tend to have numerous colds.
There is also evidence that smokers are more likely to catch colds and to have longer-lasting symptoms than nonsmokers. Tobacco smoke paralyzes the hairlike projections that line the nose and throat. Thus, these cilia are less efficient at moving mucus out.
In one sense every cold is your last—from that particular virus for a period of time. One compensation for growing older is that you develop immunity to a progressively larger number of viruses and thus catch fewer colds. By age 60, most people have an average of one cold per year, if any.
Symptoms of Common Cold
- Runny nose (discharge is usually clear, but may be yellow, or greenish)
- Nasal congestion
- Sore or scratchy throat, with hoarseness
- Inflamed membranes in the nose and throat, which may cause discomfort day and night
- Fatigue and general malaise
- Occasional low-grade fever (more often in children)
- Muscle aches and pains
Colds and the Weather Factor
Colds do occur seasonally—peak periods in the United States are September, October, and early spring—and it is hard to keep from blaming them on the weather. Puzzlingly enough, researchers have never been able to connect cold viruses with the weather. (One theory says that people catch colds in September because the schools open then, and the most susceptible population—that is, children—begins transmitting viruses.)
Getting chilled or undergoing rapid weather changes cannot cause you to catch cold. At least in the laboratory, low temperatures do not seem to increase susceptibility. In one study reported in the New England Journal of Medicine, one group of volunteers in a 40°F environment was exposed to cold viruses, while another group received its viruses in an environment warmed to 86°F. Both groups caught colds at about the same rate.
Some people believe winter is a prime time for colds because indoor heat removes humidity from the air, which dries out your nasal passages and makes you more susceptible. But while dry air may make you feel more uncomfortable, there is no evidence that it increases your susceptibility.
What Causes Common Cold?
Researchers know more than they used to about how colds are transmitted and about the viruses that cause them. Rhinoviruses tend to infect people in late summer and early autumn. Other types of viruses, not so well understood, are more likely to cause winter and early spring colds.
A sure way to “catch” a cold virus to which you are not already immune is to get a dose of it directly in the upper nose, where the temperature and humidity are ideal for its growth. In laboratory experiments, putting rhinovirus in the noses of volunteers almost always gives them a cold, no matter what their state of physical or emotional resistance or whether they are cold and wet or warm and dry.
Three possibilities exist for the way cold viruses get into your nasal passages: they may travel through the air (from the sneezing or coughing of others); they may be transmitted through direct contact (shaking hands with a cold sufferer, for example, and then touching your eyes or nose); or they may spread via a telephone, toy, or cup used by a cold sufferer. One study has found that airborne transmission is common in adults, whereas children tend to transmit secretions directly.
But, in fact, unless the virus gains access to the upper nose, the body has many lines of defense against it. Simply putting a cold virus near the nose usually has no effect, because it cannot penetrate the skin. The mucous membranes of the mouth are usually an effective barrier, so that kissing is not an efficient way to spread a cold. Simply being in the same room with a cold sufferer won’t do it. Workers in the same office usually don’t share colds. They may have colds at the same time, but they are usually due to different viruses.
Family members, though, do tend to share their colds. The three factors that primarily influence transmission are the amount of time spent around the cold sufferer, the volume of his secretions, and the amount of virus in them.
What If You Do Nothing?
People seldom develop serious complications from colds. The discomfort can be debilitating‚ but a cold is by definition temporary and self-limiting. Most colds last a week or less, but two-week colds are not unheard of.
Cold Products: Are They Helpful?
There are more than 800 over-the-counter cold remedies that promise to alleviate your symptoms. Some of the ingredients in these products can provide a degree of temporary relief. But many products contain multiple ingredients, which may actually work against one another and also increase the risk of side effects. Moreover, none of them may prove to be helpful.
If you do want to try a remedy, chose a product to match the symptoms that are really bothering you.
- Decongestants open nasal passages temporarily and may dry up mucus. If overused, however, they can have a rebound effect—an increase in swelling and congestion. In some people they can elevate blood pressure and induce insomnia. In October 2012, the U.S. Food and Drug Administration (FDA) issued a warning to consumers to keep OTC and prescription nasal sprays out of the reach of young children. Accidentally swallowing these products can cause serious symptoms, such as nausea, vomiting, lethargy (sleepiness), tachycardia (fast heart beat) and coma, that may require hospitalization.
- Cough syrups come in two types, suppressants and expectorants. The latter can help to loosen mucus if you’re congested. For a dry, nonproductive cough, suppressants may help you get a good night’s sleep. But don’t use them during the day—the coughing serves a useful purpose by clearing secretions from your throat.
- Over-the-counter NSAIDs, such as aspirin and ibuprofen, as well as acetaminophen, can relieve fever and muscle aches. Children age 19 and younger should not take aspirin for fever because of the risk of Reye’s syndrome. Pregnant women, especially in the last trimester, should avoid NSAIDs.
- Antihistamines are actually intended for hay fever, but are included in cold products. They may make mucus too thick, and thus difficult to expel by coughing. They can also induce drowsiness. It’s best to avoid them for cold relief.
Can Supplements Help?
Several dietary supplements are promoted as cold remedies:
Vitamin C. Though megadoses of vitamin C have been highly touted as a means of preventing a cold, no clinical trial has ever shown vitamin C to be more than marginally useful. At most it may shorten the duration of a cold by an insignificant amount. Megadoses of vitamin C—defined as more than 10 times the recommended dietary allowance (RDA) of 90 milligrams—may cause side effects, including nausea, abdominal cramps, and diarrhea.
Echinacea. This herb is prescribed in Germany for colds and flu, but studies have yielded conflicting results. The plant is a complicated mix of chemicals; some might actually stimulate the immune system or promote healing. But you don’t know what you’re getting in the bottle, and little is known about the plant’s toxicity.
Zinc. The evidence on zinc is mixed. A few studies have indicated that taking zinc lozenges soon after the onset of symptoms can help shorten the duration of a cold. Yet in other studies, cold sufferers taking the lozenges were just as likely as those taking placebo pills to still have the cold after seven days. There is no evidence zinc will actually prevent a cold.
N-acetylcysteine (NAC). NAC has been used to treat bronchitis and other lung conditions as an expectorant or mucous thinner as well as an anti-inflammatory.
Antibiotics: Too Many, Too Often
Antibiotics are truly “miracle drugs.” Many terrifying infectious diseases of the past, such as strep infections and bacterial pneumonia, are usually easily curable with a course of these agents. But, tragically, these miracle drugs are losing their power, as many bacteria are becoming resistant to them. In large part, this resistance is due to the enormous amount of antibiotics used by humans, for ourselves as well as in animals and agriculture. The more often antibiotics are used, the more often bacteria have the opportunity to mutate into new, resistant strains.
Each year in the United States, doctors write about 100 million prescriptions for antibiotics—the equivalent of nearly one pound of antibiotic drugs for every person. Yet probably half of all of the prescriptions are unnecessary. Most of this unnecessary prescribing is for upper respiratory infections including colds, which are caused by viruses, as are the vast majority of sore throats and coughs. No antibiotic ever killed a virus.
Why are doctors writing so many inappropriate prescriptions? They may be motivated by pressure to deal with patients quickly (it takes much more time to explain why an antibiotic is not needed than to write a prescription for one). And patients often demand the drugs (“whenever I get this cough, the antibiotic seems to clear it right up”).
What you can do. Most important, do not ask for antibiotics for a cold, a sore throat, or a cough. Also, don’t stockpile antibiotics for use in an “emergency.” (“I’ve got a meeting tomorrow—this should help.”) If you think you may have a bacterial infection, ask your physician for an examination. If antibiotics are prescribed for a bacterial infection, always complete the entire course.
Home Remedies for Common Cold
Colds cannot be cured by antibiotics, including penicillin, or any other drug. Nor is it wise to take antibiotics in an attempt to prevent later bacterial infection. Take antibiotics only when your doctor prescribes them—and certainly don’t take them on your own for a cold or flu.
Your symptoms, however uncomfortable, are a sign that your body’s defenses are working against the virus. Keep the following pointers in mind for your general well-being.
- Don’t automatically “take something” for a cold. Over-the-counter cold remedies won’t necessarily make you feel better. If you do use them, do so sparingly. Also, don’t insist on giving medicine or vitamins to a child. Many cold medications made for adults contain ingredients that are harmful when taken by children.
- Gargle to ease a sore throat. A salt or sugar-water gargle (one-quarter teaspoon of salt or one tablespoon of Karo syrup added to eight ounces of water) can be helpful in relieving sore throat symptoms.
- Saline nose drops may clear nasal passages. Like the gargle, these can also be made with one-quarter teaspoon of salt to eight ounces of water.
- Choose your fluids. “Drink plenty of fluids” is time-honored advice, but there is no evidence that increasing fluid intake will do anything but increase the need to urinate. Drink as many fluids as you want—they ease a dry throat—but you don’t need to force yourself or anyone else to consume liquids. Hot drinks, on the other hand, are definitely comforting. In one study chicken soup (as compared with cold water and hot water) was shown to increase the flow of nasal secretions. The taste and aroma was thought to be part of the therapy, as well as inhalation of the vapor. Some other hot soup might do as well, if you prefer it. Tea with honey isn’t bad, either.
- Skip the hot toddies. Hot alcoholic beverages or a shot of brandy may sound tempting, but alcohol dilates blood vessels and may produce more nasal congestion. Overindulgence, obviously, may bring on stomach upset and headache. Pregnant women are advised never to drink.
- Rest if you feel like it. Bed rest will not cure a cold or even alleviate symptoms, but if you feel exhausted or your symptoms are distractingly painful, rest at home—either in bed or just around the house.
- Increased humidity in the air you breathe can sometimes make you feel better, at least temporarily. Hot-water vaporizers offer some advantages, but can cause burns and scalding. For safety’s sake, use a cool-mist vaporizer or humidifier. There is no value in adding medications to the water. Remember that humidifiers can harbor molds, which may cause allergic reactions. Clean the tank daily, rinsing with a mild solution of chlorine bleach and refilling with fresh water.
- Ease up on exercise. There’s no harm in exercising if you feel up to it, but you should never force yourself if you feel too tired or unfit, or if you have a fever. A break of two or three days in your exercise program won’t be a significant setback.
- Do not smoke. Stop smoking and avoid secondhand smoke, which can make cold symptoms worse. Smoking aggravates the throat and interferes with microscopic infection-fighting "fingers" (called cilia) that remove the bacteria from your throat.
- Soothe your red, sore nose and lips. The irritation, which is caused by mucous secretions and aggravated by nose blowing, can often be relieved with petroleum jelly or skin lotion.
- Consider keeping kids at home for a day. If a child has a cold, going to school will do him no harm. But for the protection of other children, a child in the first stages who has a severe runny nose should probably stay at home. The most infectious period generally begins about a day before symptoms appear and lasts only another day or two.
- Wash your hands—often. The most effective way to keep a cold from spreading is hand washing. If you have a cold, remember that it spreads via your fingers, so wash them often in soap and warm water. If you are around people with colds, wash your hands often and try to avoid putting your fingers to your nose and eyes.
- Try not to share objects with cold sufferers. This means not touching their telephones, pencils, typewriters and other tools, drinking glasses, or towels. Paper towels and paper cups are worthwhile investments during cold season. See that used tissues are disposed of promptly and properly. They should be discarded in a plastic-lined receptacle or paper bag, or in any manner that makes rehandling them unnecessary.
Beyond Home Remedies: When To Call Your Doctor
There is virtually nothing a doctor can do for a cold. But contact your doctor if you have any of the following symptoms, which may seem cold-like but can indicate something more serious.
- High fever
- Shortness of breath
- Severe pain in the stomach, chest, head or ears
- Enlarged neck glands
- Coughing up a large amounts of mucus, severely painful sore throat that interferes with swallowing or severe runny nose that persists for more than a week
- For children: shortness of breath or wheezing (particularly difficult breathing), marked irritability or lethargy
Don't assume that a nasal discharge that thickens and looks greenish indicates a bacterial infection. By itself, a greenish secretion is nothing to worry about. It is not caused by invading bacteria, but is part of your immune system’s response to the cold virus, and does not call for antibiotics.
What Your Doctor Will Do
The ears, nose, throat, and chest will be examined, and a chest x-ray may be taken. If a bacterial infection is diagnosed, your doctor may prescribe an antibiotic. But if a cold is found to be uncomplicated, home treatment is the most likely recommendation.
The Complete Home Wellness Handbook
John Edward Swartzberg, M.D., F.A.C.P., Sheldon Margen, M.D., and the editors of the UC Berkeley Wellness Letter
Updated by Remedy Health Media