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Colds and the flu

Description

An in-depth report on the diagnosis, treatment, and prevention of colds and flu.

Alternative Names

Influenza; Strep throat; Bird flu; Avian influenza

Treatment

The following are some food and fluid recommendations. Most will not cure a cold but may help a person deal better with the symptoms:

• Drinking plenty of fluids and getting lots of rest when needed is still the best bit of advice to ease the discomforts of the common cold. Water is the best fluid and helps lubricate the mucous membranes. (There is no evidence that drinking milk will increase or worsen mucus, although milk is a food and should not serve as fluid replacement.)
• Chicken soup does indeed help congestion and body aches. The hot steam from the soup may be its chief advantage, although laboratory studies have actually reported that ingredients in the soup may have anti-inflammatory effects. In fact, any hot beverage may have similar soothing effects from steam. Ginger tea, fruit juice, and hot tea with honey and lemon may all be helpful.
• Spicy foods that contain hot peppers or horseradish may help clear sinuses.
• Foods rich in vitamins A and C are always recommended and may be helpful during a respiratory infection. They include oranges, kiwi, and tomatoes for C and sweet potatoes, spinach, and broccoli for A.

Vitamins

Different studies have found that large doses of vitamin C reduce the duration of a cold by a range of 5 - 50%. Some precautions against taking high doses of vitamin C include the following:

• High doses of vitamin C may cause headaches and intestinal and urinary problems and even kidney stones.
• Because ascorbic acid increases iron absorption, people with certain blood disorders, such as hemochromatosis, thalassemia, or sideroblastic anemia, should particularly avoid high doses.
• Large doses can also interfere with anticoagulant medications, blood tests used in diabetes, and stool tests.
• Vitamin E or multivitamin supplements do not appear to be helpful in reducing symptoms of the cold.

Zinc

Zinc appears to have certain important effects on the immune system and it may have a direct effect on viruses. How it works is not entirely clear, however. Zinc preparations in lozenge or nasal gel form are now available as cold treatments. Studies are very mixed on the effects of zinc on colds. The variance may be due to different zinc preparations. Studies are underway to determine advantages, if any. Some examples include the following:

• A nasal gel (Zicam), which contains zinc gluconate, has shown some success, possibly because the gel sticks to the nasal passages long enough for the zinc to interact with the virus. In a 2003 study, for example, the nasal gel shortened the duration and severity of the cold compared to placebo when it was started within 14 to 48 hours of the onset of symptoms. The supports earlier studies reporting that it shortened the duration of a cold by about two days.
• Zinc lozenges are showing mixed results. One 2000 study suggested that the use of zinc acetate lozenges (e.g., Fast-Dry, Galzin) may be more effective and have a better taste than other formulations, such as zinc gluconate (Cold-Eeze, Orazinc). On the other hand, a 2002 study reported that zinc gluconate reduced cold duration significantly. To further confuse matters, the two zinc lozenge preparations were directly compared in a 2000 study, and neither was effective. The reasons for these conflicting results are not clear.
• A small 2001 study on a nasal spray preparation found no benefits. The spray preparation had less zinc than the nasal gel.

In any case, no one with an adequate diet and a healthy immune system should take zinc for prolonged periods for preventing colds.

Side Effects. Side effects, particularly of the lozenge form, include the following:

• Dry mouth
• Constipation
• Nausea
• Bad taste (possibly only with zinc gluconate lozenges)
• Severe vomiting, dehydration, and restlessness (signs of overdose, seek medical help)
• Allergic response (rare)

Food and Drug Interactions. Zinc may also interact with drugs or other elements:

• It may reduce absorption of certain antibiotics.
• Foods high in calcium or phosphorus may reduce zinc absorption.
• In high doses and for long periods of time, zinc can cause copper deficiencies.

Medications for Mild Pain and Fever Reduction

Many people take medications to reduce mild pain and fever. Adults most often choose aspirin, ibuprofen (Advil), or acetaminophen (Tylenol).

The following are recommendations for children:

• Acetaminophen (Tylenol) or ibuprofen (usually Advil or Motrin) are the typical pain-relievers parents give their children. Most pediatricians advise such medications for children who run fevers over 101° F. Some suggest alternating the two agents, although there is no evidence that this regimen offers any benefits, and it might be harmful.
• Aspirin and aspirin-containing products are virtually never recommended for children or adolescents. Reye Syndrome, a very serious condition, has been associated with aspirin use in children who have flu symptoms or chicken pox.

Some studies are suggesting that these anti-fever agents may actually reduce the body's immune response against cold and flu viruses and prolong symptoms. A 2000 study, for example, reported a longer flu duration in people who took aspirin or acetaminophen (although people still felt better). (In the study, these drugs did not appear prolong other illnesses, including Rocky Mountain spotted fever and shigellosis.) Nevertheless, most doctors strongly recommend lowering fevers in children, since high fevers can sometimes cause seizures.

Nasal Strips

Nasal strips (such as Breathe Right) are placed across the lower part of the nose and pull the nostrils open. These strips may open the nasal passages and ease congestion due to a cold, sinusitis, or hay fever. As of yet, there is no scientific evidence that they offer such benefits.

Nasal Wash

A nasal wash can be helpful for removing mucus from the nose. A saline solution can be purchased at a drug store or made at home. One study reported that neither a homemade solution (using one teaspoon of salt and one pinch of baking soda in a pint of warm water) nor a commercial hypertonic saline nasal wash had any effect on symptoms. Further, one preliminary study found that over-the-counter saline nasal sprays that contain benzalkonium chloride as a preservative may actually worsen symptoms and infection.

Some physicians, however, advocate a traditional nasal wash that has been used for centuries and is different from that used in the study. It contains no baking soda and uses more fluid for each dose and less salt. The nasal wash should be performed several times a day.

A simple method for administering a nasal wash:

• Lean over the sink head down.
• Pour some solution into the palm of the hand and inhale it through the nose, one nostril at a time.
• Spit the remaining solution out.
• Gently blow the nose.

The solution may also be inserted into the nose using a large rubber ear syringe, available at a pharmacy. In this case the process is the following:

• Lean over the sink head down.
• Insert only the tip of the syringe into one nostril.
• Gently squeeze the bulb several times to wash the nasal passage.
• Then press the bulb firmly enough so that the solution passes into the mouth.
• The process should be repeated in the other nostril.

Nasal-Delivery Decongestants

Nasal-delivery decongestants are applied directly into the nasal passages with a spray, gel, drops, or vapors. Nasal forms work faster than oral decongestants and have fewer side effects. They often require frequent administration, although long-acting forms are now available. Ingredients and brands of nasal decongestants include the following:

Long Acting Nasal-Delivery Decongestants. They are effective in a few minutes and remain so for 6 - 12 hours. The primary ingredient in long-acting decongestant is:

• Oxymetazoline: Brands include Vicks Sinex (12-hour brands), Afrin (12-hour brands), Dristan 12-Hour, Good Sense, Nostrilla, Neo-Synephrine 12-Hour
• Xylometazoline: Inspire, Otrivin, Natru-vent

Short-Acting Nasal-Delivery Decongestants. The effects usually last about 4 hours. The primary ingredients in short-acing decongestants are:

• Phenylephrine: Neo-Synephrine (mild, regular, high-potency), 4-Way, Dristan Mist Spray, Vicks Sinex
• Naphazoline (Naphcon Forte, Privine)

Dependency and Rebound. The major hazard with nasal-delivery decongestants, particularly long-acting forms, is a cycle of dependency and rebound effects. The 12-hour brands pose a particular risk for this effect. This effect works in the following way:

• With prolonged use (more than 3 - 5 days), nasal decongestants lose effectiveness and even cause swelling in the nasal passages.
• The patient then increases the frequency of their dose. The congestion worsens, and the patient responds with even more frequent doses, in some cases as often as every hour.
• Individuals then become dependent on them.

Tips for Use. The following precautions are important for people taking nasal decongestants:

• When using a nasal spray, spray each nostril once. Wait a minute to allow absorption into the mucosal tissues, and then spray again.
• Keep the nasal passages moist. All forms of nasal decongestants can cause irritation and stinging. They also may dry out the affected areas and damage tissues.
• Do not share droppers and inhalators with other people.
• Use decongestants only for conditions requiring short-term use, such as before air travel or for a single-allergy attack. Do not take them more than 3 days in a row. With prolonged use, nasal decongestants become ineffective and result in the so-called rebound effect and dependence.
• Discard sprayers, inhalators, or other decongestant delivery devices when the medication is no longer needed. Over time, these devices can become reservoirs for bacteria.
• Discard the medicine if it becomes cloudy or unclear.

Oral Decongestants

Oral decongestants also come in many brands, which mainly differ in their ingredients. The most common active ingredient is pseudoephedrine (Sudafed, Actifed, Drixoral).

Side Effects of Decongestants. Decongestants have certain adverse effects, which are more apt to occur in oral than nasal decongestants and include the following:

• Agitation and nervousness
• Drowsiness (particularly with oral decongestants and in combination with alcohol)
• Changes in heart rate and blood pressure
• Avoid combinations of oral decongestants with alcohol or certain drugs, including monoamine oxidase inhibitors (MAOI) and sedatives

In November 2000, the Food and Drug Administration (FDA) banned products, including decongestants, which contained phenylpropanolamine (PPA). This action was in response to a few reports of an increased risk of stroke. (Stroke tended to occur in people who took diet suppressants containing PPA rather than decongestants. In any case, serious events were still very rare.) All major brands that previously contained PPA have now substituted other active ingredients (usually pseudoephedrine) and are safe to use. Anyone with old forms of any decongestant should check the labels and discard them if they contain phenylpropanolamine. It should be noted that PPA has been used in dozens of medications for over 50 years. Extreme concern, therefore, is unwarranted.

Individuals at Risk for Complications from Decongestants. People who may be at higher risk for complications are those with certain medical conditions, including disorders that make blood vessels highly susceptible to contraction. Such conditions include the following:

• Heart disease
• High blood pressure
• Thyroid disease
• Diabetes
• Prostate problems that cause urinary difficulties
• Migraines
• Raynaud's phenomenon
• High sensitivity to cold
• Emphysema or chronic bronchitis

People taking medications that increase serotonin levels, such as certain antidepressants, anti-migraine agents, diet pills, St. John's Wort, and methamphetamine. The combinations can cause blood vessels in the brain to narrow suddenly, causing severe headaches and even stroke.

Anyone with these conditions should not use either oral or nasal decongestants without a doctor's guidance. Other groups who should also use these agents with caution are the following:

• Anyone who is pregnant should not use these agents without consulting a physician.
• Children appear to metabolize decongestants differently than adults. Decongestants should not be used at all in infants and small children, who are at particular risk for side effects that depress the central nervous system. Such symptoms cause changes in blood pressure, drowsiness, deep sleep, and, rarely, coma.

Cough Remedies

Major studies have indicated that over-the-counter cough medicines are not very effective, but they are also not harmful.

• For thick phlegm, patients may try cough medications that contain guaifenesin (Robitussin, Scot-Tussin Expectorant), which loosens mucus. Patients should not suppress coughs that produce mucus and phlegm. It is important to expel this substance. To loosen phlegm, patients should drink plenty of fluids and use a humidifier or steamer.
• For patients with a dry cough, a suppressant may be useful, such as one that contains dextromethorphan (Drixoral Cough, Robitussin Maximum Strength Cough Suppressant).

Medications that contain both a cough suppressant and an expectorant are not useful and should be avoided. Medicated cough drops that contain dextromethorphan are not very useful. A patient is just as likely to find relief from hard candy or lozenges.

Children and Cough and Cold Medicines

In early 2007, the Food and Drug Administration (FDA) began reviewing the safety of common cough and cold remedies for children, following a survey by the Centers of Disease Control and Prevention (CDC). According to the CDC survey, 1,519 children under age 2 were treated between 2004 - 2005 in emergency departments for adverse side effects associated with cough and cold medicines. Three infants ages 1 - 6 months died in 2005. All three had high levels of pseudoephedrine, a nasal decongestant, in their blood. The FDA warns that parents should not give cough and cold medications to children under age 2 without first consulting a health care provider.

Remedies for Sore Throat Associated with Colds

Sore throats that are associated with colds are generally mild. The following may be helpful:

• Cough drops, throat sprays, or gargling warm salt water may help relieve sore throat and reduce coughing.
• Throat sprays that contain phenol (for example, Vicks Chloraseptic) may be particularly helpful. Phenol has antibacterial properties. In one study, patients with sore throat who used the spray experienced faster resolution of the cold itself, including fever, headache, and other symptoms compared to a dummy medication. The patients were not taking antibiotics.
• Cough drops that contain menthol and mild anesthetics, such as benzocaine, hexylrescorincol, phenol, and dyclonine (the most potent), may soothe a mild sore throat.
• One health professional suggested that people with sore throats from postnasal drip might try taking a teaspoon of liquid antacid. They shouldn't drink anything afterward, since the intention is to coat the throat and help neutralize the acid in the mucus that might be causing pain.

If soreness in the throat is very severe and does not respond to mild treatments, the patient or parent should check with the physician to see if a strep throat is present, which would require antibiotics. In one study only 17% of sore throats in adults were caused by Group A streptococcus, the bacterium responsible for strep throat. Nevertheless, antibiotics were prescribed in 73% of patients.

Combination Cold and Flu Remedies and Antihistamines

Dozens of remedies are available that combine ingredients aimed at more than one cold or flu symptom. In general, they do no harm, but they have the following problems:

• Some ingredients may produce side effects without even helping a cold.
• In some cases, the ingredients conflict (such as a cough expectorant and a cough suppressant).
• In other cases, a patient may wish to increase the dosage to improve one symptom, which serves to increase other ingredients that do no good and, in higher doses, may cause side effects.

Note on Antihistamines. Many combination remedies contain antihistamines. Antihistamines are used for allergies and not generally recommended to relieve the symptoms of the common cold. Some evidence suggests, however, that they may have some value.

One study has indicated that older so-called first-generation antihistamines may reduce cold symptoms. Experts theorize that their benefits for the cold are likely to be due to the drowsiness they cause. Such antihistamines include Benadryl, Tavist, and Chlor-Trimeton. The newer, second-generation antihistamines (Claritin, Allegra, Zyrtec) do not have these effects and also appear to have no benefits against colds.

Another study reported high levels of histamine in the urine of patients infected with type A influenza, suggesting that antihistamines may actually have some real value for viral infections, include flu and colds. More research is needed, however, before the significance of these findings is known.

Herbs and Supplements Herbal remedies and dietary supplements are not regulated by the FDA. This means that manufacturers and distributors do not need FDA approval to sell their products. In addition, any substance that affects the body's chemistry can, like any drug, produce side effects that may be harmful. There have been numerous reported cases of serious and even deadly side effects from herbal products. The following are special concerns for people taking natural remedies for colds or influenza: Echinacea is commonly taken to prevent onset and ease symptoms of cold or flu. A rigorous study, published in 2005 in the New England Journal of Medicine , determined that this herb does not help to prevent or treat colds. In addition, some people are allergic to echinacea. People who have autoimmune diseases or plant allergies should avoid it. There have been a few reports of people experiencing a skin reaction called erythema nodosum, which is characterized by tender, red nodules under the skin. Grapeseed extract is sometimes touted as a natural antihistamine. A 2002 study, however, reported no benefits from it. Chinese herbal cold and allergy products can contain trace amounts of aristolochic acid, a chemical that causes kidney damage and cancer. Many herbal remedies imported from Asia may contain potent pharmaceuticals, such as phenacetin and steroids, as well as toxic metals.

• Review Date: 3/6/2007
• Reviewed By: A.D.A.M. Editorial Team: Greg Juhn, M.T.P.W., David R. Eltz, Kelli A. Stacy. Previously reviewed by Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital (12/4/2006).

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