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Colds and Influenza (the Flu)

* Please note that most treatment modalities listed below are based on conventional medicine. PreventDisease.com does advocate the use of any pharmaceutical drug treatments. Long-term drug therapy is detrimental to human health. All drug information is for your reference only and readers are strongly encouraged to research healthier alternatives to any drug therapies listed.

WHAT ARE COLDS AND FLU?

Upper Respiratory Tract Infections

Upper respiratory tract infections affect the airways in the nose, ears, and throat. They can be caused by viruses, bacteria, or other microscopic organisms. In most cases these infections are colds or mild influenza (flu) and are temporary and harmless. In rare cases, flu can be severe or the infections may affect the throat, ears, or sinuses or even evolve into pneumonia. [For information on other upper respiratory tract infections, see also the Reports #64 Pneumonia, #78 Ear Infections (Otitis Media) in Children, and #62 Sinusitis.]

Organisms that cause these upper respiratory tract infections are generally spread by the following:

Direct contact (such as hand-to-mouth).
Coughing or sneezing droplets that contain the organisms in the air.

The Common Cold

The common cold (medically known as infectious nasopharyngitis) is the most common upper respiratory tract infection. More than 200 viruses can cause colds, the most common being the rhinovirus, which causes more infections in humans than any other microorganism. It usually takes between one and three days from exposure to the virus until symptoms wear off.

Symptoms of a common cold are mild and include the following:

Nasal congestion.
Muscles aches.
Fatigue.
Fever.
Mild sore throat.

A cold usually progresses in the following manner:

It nearly always starts rapidly with throat irritation and stuffiness in the nose.
Within hours, full-blown cold symptoms usually develop, which can include sneezing, mild sore throat, low-grade fever (in adults), minor headaches, muscle aches, and coughing.
Fever in adults is low-grade. In children, however, fever may be as high as 103 degrees F for one or two days; it should go down after that and be normal by the fifth day.
Nasal discharge is usually clear and runny the first one to three days. It then thickens and becomes yellow to greenish.
The sore throat is usually mild and lasts only about a day. A runny nose usually lasts two to seven days, although coughing and nasal discharge can persist for more than two weeks.

Influenza

Influenza, commonly called the flu, is always caused by a virus. The symptoms usually occur as follows:

Abrupt onset of severe symptoms.
Symptoms include headache, muscle aches, fatigue, and high fever (up to 104 degrees F).
Influenza may also cause a cough (which is usually dry but can be severe) and sometimes a runny nose and sore throat.
Children may experience vomiting and diarrhea as well as other flu symptoms.

The Influenza Viruses. Viruses are basically gene packages wrapped in protein membranes and coated with a fatty envelope spiked with glycoproteins. Three strains of influenza have been identified depending on whether they have one or two membranes and the make-up of the glycoprotein spikes. The major influenza strains are referred to as A, B, and C:

Type A is the most widespread and can even infect animals. Based on analyses of strains in October 2000, nearly 60% were type A and about 40% were type B. Influenza A is the cause of the major pandemics (worldwide epidemics) of influenza that have occurred.
Type B is less common and tends to be less severe; it infects only humans.
Type C causes only mild disease.

HOW ARE COLDS AND INFLUENZA DIAGNOSED?

Differentiating Between a Cold and Flu

Differentiating between a cold and flu is often one of degree and may be difficult. Cold symptoms are nearly always milder than those of the flu. [ See Table Comparing Colds and Flus.] :

Comparing Colds and Flus

Symptoms	Cold	Flu
Fever	Rare	Common and high (102-104°F); lasts 3-4 days.
Headache	Rare	Almost always present.
General aches and pains	Mild	Often severe.
Fatigue, exhaustion, and weakness	Mild	Extreme exhaustion is early and severe. Fatigue and weakness can last two to three weeks.
Stuffy nose	Nearly always	Sometimes.
Sneezing	Very common	Sometimes.
Sore throat	Common	Sometimes.
Chest discomfort and cough	Mild to moderate, hacking cough	Common, can be severe.
From National Institute of Allergy and Infectious Disease.

Diagnostic Tests for Influenza

Tests have required taking samples by applying suction through a catheter inserted into the nose. This approach is uncomfortable, particularly in children. Newer faster tests now are available for diagnosing influenza A and B. They use samples obtained with a swab from one nostril and can provide results in only about ten minutes. The swab test is even available over-the-counter in some European countries.

Ruling out Other Causes of Congestion

Ruling out Allergic Rhinitis. Symptoms of allergic rhinitis include nasal obstruction and congestion, which are similar to the symptoms of a cold. People with allergies, however, are apt to have the following:

Thin, clear, and runny nasal discharge.
An itchy nose, eyes, or throat.
Recurrent sneezing.

There are two forms of allergic rhinitis:

Symptoms that appear only during allergy season (spring or fall) are called seasonal rhinitis (commonly known as hay or rose fever).
Allergens in the house, such as house dust mites, molds, and pet dander, can cause year-long allergic rhinitis, referred to as perennial rhinitis.

[For more information see the Report on Allergic Rhinitis and Chronic Nasal Congestion.]

Ruling out Sinusitis. The signs and symptoms suggestive of true acute sinusitis include the following:

A return of congestion and discomfort after initial improvement in a cold (called double sickening).
Purulent (pus-filled) nasal secretion.
A lack of response to decongestant or antihistamine.
Pain in the upper teeth or pain on one side of the head.
On leaning forward, facial pain above or below both eyes.

Children with sinusitis are less likely to have facial pain and headache and may only develop a high fever or prolonged upper respiratory symptoms (eg, a daytime cough that does not improve for 11 to 14 days). When the diagnosis is unclear or complications are suspected, further tests may be required. [For more information see the Report on Sinusitis.]

Ruling out Other Causes of Sore Throat

In addition to common cold viruses, other, less frequent causes of sore throat include the following:

Strep throat. [See Box "Strep Throat."] :
Sore throat related to influenza.
Foodborne and waterborne infections (Streptococcus C and G). These agents mimic strep throat but are usually less severe and do not cause rheumatic fever.
Sore throat and tonsillitis caused by Arcanobacterium haemolyticum . This is a rare cause of sore throat and tonsillitis in young people and adults. It also mimics strep throat and may even cause a rash. It should be suspected in patients with symptoms that suggest strep but no laboratory evidence of strep. It can be treated with erythromycin.
Infectious mononucleosis. Mononucleosis ("mono") is caused by the Epstein-Barr virus. It usually occurs in adolescents and young adults. Sore throat is accompanied by chills, fever, swollen glands, and fatigue. Treatment involves avoiding vigorous activities for the first one or two months and managing symptoms.
Herpesvirus. The herpesvirus 1 may cause severe sore throat, most often in college students.
Pneumonias caused by the atypical organisms mycoplasma or chlamydia. These forms of pneumonia typically occur in young adults and may cause sore throat as well as fever and cough.

STREP THROAT

What is Strep Throat?

Group A Streptococcal bacteria, known commonly as "strep throat," is the most common bacterial cause of a severe sore throat. Strep throat occurs mostly in school age children, but people of all ages are susceptible. (It should be noted that strep throat constitutes only about 12% of all sore throat cases seen by doctors.)

The symptoms of strep throat include the following:

A sudden onset of severe sore throat.
Difficulty in swallowing.
Fever.
The patient may also have a headache, stomach pain, and vomiting.

Only about half of patients with strep throat have such clear cut symptoms, however. Furthermore, half of people who have these symptoms do not actually have strep throat.

How Is Strep Throat Diagnosed?

Most cold-related sore throats are caused by viruses and require no treatment. They usually do not last more than a day. When the sore throat persists and is very painful the physician will want to rule out or confirm the presence of group A Streptococcal bacteria, the cause of strep throat, which can be treated with antibiotics.

The physician will take the following steps when strep throat is suspected:

Look for redness, swelling, and pus-filled patches on the tonsils and back of the throat.
Feel the sides of the neck for swollen lymph nodes.
Use a cotton swab to take a sample of pus in the throat for a throat culture.

Throat Culture. A culture taken from the throat sample is the most effective and least expensive test for confirming the presence of the Streptococcal bacteria.

The sample is sent to a laboratory, where it is cultured; that is, the sample is added to special substances so that any bacteria present will reproduce.
It takes between 24 hours and 48 hours to obtain a result.

Rapid Antigen-Detection Test for Strep Throat. A faster test called the rapid strep antigen test uses chemicals to detect the presence of bacteria in a few minutes. A positive result nearly always means that Streptococcal bacteria is the cause of the infection. The test, however, fails to detect between 10% and 20% of cases, and so a culture may still be necessary to catch any missed infections, particularly in children.

How Serious is Strep Throat?

The use of antibiotics has removed the threat of most complications from streptococcus infection in the throat (strep throat). However, untreated strep throat could lead to the following complications:

Abscess in the tonsils.
Scarlet fever.
Rheumatic fever. This condition, although very rare in the US, can injure the heart and have long term serious effects.

How Is Strep Throat Treated?

Antibiotics. Throat infections caused by group A Streptococcal bacteria (strep throat) require antibiotics. The following are generally used:

Penicillin is usually the antibiotic of choice unless the patient is allergic. A full 10 days may be necessary. Amoxicillin, a form of penicillin, is proving to be effective when taken in a single daily dose for ten days.
Macrolide antibiotics. Erythromycin is known as a macrolide antibiotic and is the first choice for patients with penicillin allergies. A 10-day regimen is needed. Another macrolide, azithromycin, can be given as a single daily dose and may be effective in five days. It is expensive, however, and bacterial resistance to macrolides is growing, so it should be not be given as a first choice.
Cephalosporins are a potent, but expensive, group of antibiotics that are very effective in eradicating the bacteria.

Many physicians will prescribe an antibiotic based on symptoms alone. Studies indicate, however, that only about half of adults and far fewer children with even strong signs and symptoms for strep throat actually have Streptococcal infections. Parents should be comforted that a delay in antibiotic treatment while waiting for lab results does not increase the risk that the child will develop serious long-term complications, including acute rheumatic fever. If a patient is severely ill, however, it is reasonable to begin administering antibiotics before the results are back. If the culture is negative (there is no evidence of bacteria), then the physician should call the family and be sure they stop taking the antibiotics and discard any remaining pills.

HOW SERIOUS ARE COLDS AND FLUS?

Complications of Colds

Colds rarely cause serious complications. In about 1% of cases, a cold can lead to other complications, such as sinus or ear infections. It can also aggravate asthma and, in uncommon situations, increase the risk for lower respiratory tract infections.

Ear Infections. The rhinovirus infection, a major cause of colds, also commonly predisposes children to ear infections, possibly by obstructing the Eustachian tube, which leads to the middle ear. Viruses may even attack the ear directly. In one study, 74% of patients with rhinovirus colds had pressure abnormalities in their middle ear. [For more information, see the Report Ear Infections (Otitis Media) in Children. ]

Sinusitis. Between 0.5% and 5% of people with colds develop sinusitis, an infection in the sinus cavities (air-filled spaces in the skull). Sinusitis is usually mild, but if it becomes severe, antibiotics generally eliminate further problems. In rare cases, however, sinusitis can be serious. [For more information see the Report Sinusitis.]

Lower Respiratory Tract Infections. The common cold poses a risk for bronchitis and pneumonia in nursing home patients and other people who may be susceptible to infection. Some experts believe that the rhinovirus may play a more significant role than the flu in causing lower respiratory infections in such people.

Aggravation of Asthma. Rhinovirus infections can acerbate asthma in both children and adults and has reported to be the most common infectious organism associated with asthma attacks. Some studies have reported the common cold being associated with between 33% and 71% of severe asthma episodes.

Complications of Influenza

In general, the flu is usually self-limited and not serious. Influenza is responsible, however, for 15% to 30% of the excess number of hospitalizations that occur in winter. About 1% of people who contract the flu end up in the hospital and, on average, 20,000 Americans die every year from complications of influenza.

Severity of Flu Strain. Influenza A is more severe than B.

Pneumonia in High-Risk Groups. Pneumonia is the major serious complication of influenza. It can develop about five days after viral influenza. It is an uncommon event, however, and nearly always occurs in susceptible individuals about five days after onset. Individuals with higher than average risk are the following:

People with weakened immune systems, such as AIDS patients.
Very Young children.
Hospitalized patients.
Drug abusers who use needles.
The elderly. Nursing homes patients are especially hard-hit by flu epidemics, with fatality rates as high as 30%.

Combinations of these factors increase the risk. It should be noted that pneumonia is an uncommon outcome of influenza in healthy adults.

Effect on People with Heart or Lung Disease. Studies suggest that influenza may increase the risk for death in people with existing heart, lung, or circulation disorders. In fact, the higher than average number of winter deaths in people with heart disease may be due only to the occurrence of influenza during those months.

Complications in Children. Children under 1 years old have a very high risk, not only for pneumonia but also for other complications, including meningitis and encephalitis (inflammations in central nervous system). The risk declines after age one but is still elevated in children aged three to five. It is often difficult to tell whether pneumonia in small children is related to influenza or caused by respiratory syncytial virus (RSV), the major viral cause of infant pneumonia. Experts estimate that about 25% of severe lung infections are due to influenza.

Pandemics. Every year, influenza strikes millions of people worldwide. Influenza epidemics are most serious when they involve a new strain against which most people are not immune. Such so-called pandemics can infect more than one fourth of the world's population within a three-month period. For example, the Spanish flu in 1918 and 1919 killed 20 million people in the US and Europe alone. Although pandemics are still of great concern, there have been major improvements in private and public health since then, including the discovery of antibiotics to treat bacterial complications, new anti-viral agents and vaccines, and world-wide surveillance of outbreaks.

WHO GETS COLDS AND FLUS?

Everyone gets a cold or upper respiratory infection at some time:

On average, Americans develop two to four colds a year, which totals to about 200 million colds a year.
An estimated 20% of Americans contract the flu each year.

Age

The very young and the very old are at higher risk for upper respiratory tract infections and for complications from them.

Young Children. Young children are prone to colds and may have eight to 12 bouts every year. Before the immune system matures, all infants are susceptible to infections, with a possible frequency of one cold every one or two months. Smaller nasal and sinus passages also make children more vulnerable than older children and adults. Infections gradually diminish as they grow, until at school age their rate is about the same as an adult's.

There is almost never cause for concern when a child has frequent colds unless they become unusually severe or more frequent than usual. Day care centers and parental smoking increase the rates of respiratory infections.

The Elderly. The elderly have diminished cough and gag reflexes and faltering immune systems and are at greater risk for serious respiratory infections than are young and middle-aged adults.

Exposure to Smoke and Environmental Pollutants

The risk of respiratory infections is increased by exposure to cigarette smoke, which can injure airways and damage the cilia (tiny hair-like structures that help keep the airways clear).

Toxic fumes, industrial smoke, and other air pollutants are also risk factors.

Medical Conditions

People with AIDS and other medical conditions that damage the immune system are extremely susceptible to serious infections.
Cancers, especially leukemia and Hodgkin's disease, put patients at risk. Patients who are on corticosteroid (steroid) treatments, chemotherapy, or other medications that suppress the immune system are also prone to infection.
People with diabetes are at higher risk for flu.
Certain genetic disorders predispose people with these problems to respiratory infections. They include sickle-cell disease, cystic fibrosis (which causes mucus abnormalities), and Kartagener's syndrome (which results in malfunctioning cilia).

People under Stress

Much evidence suggests that stress increases one's susceptibility to a cold perhaps by increasing specific immune factors that cause inflammation in the airways.

In one study, people with high stress levels averaged 2.7 upper respiratory infections during a six-month period and those reporting low stress averaged 1.5 infections.
In another well-conducted study, high-stress individuals were 1.7 times more likely to have a cold than low-stress people.

Stress appears to increase the risk for a cold regardless of lifestyle or other health habits. And once a person catches a cold or flu, stress can exacerbate symptoms.

Excessive Exercise

Although long-term effects of regular exercise are known to improve health, the immediate effect of exercise on the immune system is uncertain:

In people who already have colds, exercise has no effect on the illness' severity or duration of the infection. People should avoid strenuous physical activity when they have high fevers or widespread viral illnesses, however.
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 events; very low fat diets appear to support this negative effect on the immune system. A higher fat-diet may help redress this imbalance (omega-3 fatty acids, found in fish and canola oil are preferred). Whether carbohydrate loading provides much additional value is not clear.

Seasonal Incidence

Cold Season. Although most people get colds in the winter, this is not due to cold weather but most likely because people spend more time indoors and are exposed to higher concentrations of rhinovirus, the cause of colds. Dry winter weather also dries up nasal passages, making them more susceptible to viruses.

Flu Season. In 2000, influenza activity started in October and lasted into mid March. Doctors' office visits significantly increased beginning in December and influenza activity peaked during the first two weeks in February.

WHAT LIFESTYLE HABITS CAN HELP PREVENT UPPER RESPIRATORY TRACT INFECTIONS?

Good Hygiene

Everyone should always wash his or her hands before eating and after going outside. Ordinary soap is sufficient. Antibacterial soaps add little protection, particularly against viruses. In fact, one study suggests that common liquid dish washing soaps are up to 100 times more effective than antibacterial soaps in killing respiratory syncytial virus (RSV), which is known to cause pneumonia.

Flus and colds are not spread by touching inanimate objects, such as subway poles or toilet seats. Bacteria or viruses do not thrive on such objects.

Healthy Diet

Daily diets should include foods such as fresh, dark-colored fruits and vegetables, which are rich in antioxidants and other important food chemicals that help boost the immune system.

Low Stress

Interestingly, maintaining an active social lifestyle could help prevent colds. One study found that the more social interaction a person has the less likely they are to have a cold, possibly because stress hormones, which suppress the immune system, are reduced.

WHAT ARE SPECIFIC AGENTS FOR TREATING COLDS?

Zinc

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. In 10 controlled studies, five showed no effect on symptoms and five reported that it shortened the duration of cold. And, in fact, in 1999, the FDA charged the manufacturer of the zinc carbonate lozenges Cold-Eeze and Kids-Eeze Bubble-Gum with making unsubstantiated claims about their benefits against colds, allergies, and pneumonia.

The variance observed in studies may be due to different zinc preparations. Studies are underway to determine advantages, if any, but results are still mixed. Some examples include the following:

One 2000 study suggested that the use of zinc acetate lozenges (eg, Fast-Dry, Galzin) may be more effective and have a better taste than other formulations, such as zinc gluconate (Cold-Eeze, Orazinc). In the study, this preparation reduced both duration and severity of symptoms compared to a dummy pill.
The two zinc lozenge preparations were directly compared in another 2000 study, however, and neither were effective.
A nasal zinc gluconate gel (Zicam), which contains zinc ions as the active ingredient, may be more effective than zinc lozenges because the zinc resides within the nasal cavity long enough to interact with the virus. In one 2000 study, patients with colds who used it achieved full recovery in an average of 2.3 days compared to 9 days in patients using a "dummy" nasal preparation. More studies are underway.

Zinc appears to have certain effects on the immune system that dampen the inflammatory response (which causes fever and aches). How it works is not entirely clear, however. In any case, no one with an adequate diet and a healthy immune syst em sho uld take zinc for prolonged periods for preventing colds.

Side Effects. Side effects include the following:

Dry mouth.
Constipation.
Nausea.
Bad taste (possibly only with zinc gluconate lozenges).
Overdose may cause severe vomiting, dehydration, and restlessness. Call a physician if any of these symptoms occur.
In rare cases, an allergic response may occur.

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.

Vitamin C

A number of studies have found that large doses of vitamin C reduce the duration of a cold by 5% to 50%, depending on the study.

Taking large doses of vitamin C after exposure to a cold virus, however, does not appear to prevent the cold from developing. In an examination of 60 studies, the six largest ones reported no preventive effects of vitamin C in well-nourished individuals. (It may be useful for prevention of respiratory infections in people in poor health or under heavy physical stress, however.)

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.

Echinacea

The herbal remedy echinacea is now commonly taken to prevent onset and ease symptoms of cold or flu. There are three species:

Echinacea (E.) purpurea.
E. pallida.
E. augustifolio .

In some studies, people who took extracts of either E. purpurea or E. augustifolio experienced no protection against colds. Preparations themselves vary, however, and effectiveness may depend on whether the root, herb, or whole plant is used. For example, in a 1999 study, a root and herb preparation of E. purpurea (Echinaforce) reduced cold symptoms while another E. purpurea root preparation did not. The drying process also effects the active chemicals in the herb. (Freeze-drying may be best.) Research is needed to determine which ones, if any, are beneficial.

Precautions. Some precautions are as follows:

At this time there are no standards or quality controls available for echinacea (including what part of the plant to use) or any other herbal remedies.
Allergic reactions have been reported. People with autoimmune diseases or who are allergic to plants in the daisy family should particularly avoid it.
There have been some reports of a reaction called erythema nodosum associated with echinacea. This involves a rash, sometimes accompanied by fever, headache, muscle and joint aches, and sore throat.

No one should take untested so-called natural remedies without a doctor's approval. No studies have confirmed the benefits of these medications and many can cause toxic side effects in large doses.

Experimental Therapies for Colds

A nasal spray, tremacamra, is under investigation for treating colds. It contains a genetically engineered compound that resembles a natural molecule called ICAM-1, which is located in human cells and attaches to rhinoviruses that are present in the nasal passages. The similar tremacamra tricks the virus into attaching to it rather than to the ICAM-1 receptor, thereby preventing the virus from affecting human cells. Studies suggest that it reduces the severity of a cold, although its effect on duration is not clear.

Several other drugs are being studied for prevention and treatment of colds. One, pleconaril, inhibits viral attachment and is also showing promise.

WHAT ARE SPECIFIC DRUGS FOR TREATING AND PREVENTIVE SEVERE INFLUENZA?

For mild flus, symptom relief is similar to that for colds. [ See What Are the Treatments for Symptoms of Colds and Mild Flu?.]

Antiviral Agents

Antiviral agents have now been developed to treat and prevent influenza A, B, or both. There are two classes of agents: M2 inhibitors and neuraminidase inhibitors.

M2 Inhibitors. Amantadine (Symmetrel) and rimantadine (Flumadine) are M2 inhibitors. They have the following benefits:

Both offer protection against influenza A and prevent severe illness if a person contracts the infection. (To be effective it must be administered within two days of onset.)
They may shorten the duration and lessen the severity of the flu if given within 48 hours of onset of symptoms.

Drawbacks of M2 inhibitors include the following:

They are not effective against influenza B (less common but more severe than A).
Viral resistance to these agents is rapidly emerging.
Both agents occasionally cause nausea, vomiting, and indigestion.
Amantadine affects the nervous system and about 10% of people experience nervousness, depression, anxiety, difficulty concentrating, and lightheadedness. Rarely, amantadine can cause hallucinations and seizures, usually in elderly people already at risk for psychiatric symptoms.
Neither has proven to reduce the risk for complications, including pneumonia and bronchitis.

Neuraminidase Inhibitors. Zanamivir (Relenza) and oseltamivir (Tamiflu) are called neuraminidase inhibitors. They are newer agents that have been designed to block a key viral enzyme, neuraminidase, which is involved with viral replication.

They have the following benefits:

Both neuraminidase inhibitors are proving to be effective for treating and preventing A and B strains of influenza. (M2 inhibitors are only effective against type A, although they are also much less expensive than neuraminidase inhibitors.)
They both shorten the duration of the flu by one to three days but need to be taken within two days of onset of symptoms.
A 2000 study on oseltamivir suggested that it may help reduce transmission of the virus.
They appear to have a lower risk than M1 inhibitors for emerging viral strains that are resistant to their effects.
There is some early evidence that they may reduce complications of influenza, although this needs to be confirmed. It is not yet known if they have any effect on overall survival rates.

Both neuraminidase inhibitors provide similar benefits but there are some differences:

Zanamivir is administered as a nasal spray or inhaler. Side effects are minor. People with asthma or other lung disorders may experience airway spasms and should use this drug with caution.
Oseltamivir comes in capsule form. Side effects are also minor but about 10% of patients experience nausea and vomiting.

Their current use in different age and patient groups are as follows:

Adults. Both are approved for treatment in adult patients.
Children. Zanamivir is also approved for children over seven. Studies are currently underway to determine the safety of oseltamivir in children. In one study, it reduced the duration of symptoms by 26% and also reduced incidence of ear infections by 44% in children ages one to 12.
High-Risk Patients. Recent studies indicate they are safe and effective in patients with serious medical problems or other conditions that put them at risk for complications of flu.

Antiviral Agents for Prevention of Influenza. Although they are not substitutes for vaccines, all antiviral agents have some preventive properties.

M2 inhibitors. Amantadine and rimantadine protect against the influenza A infection itself in about half of individuals. Rimantadine is preferred for prevention during outbreaks of influenza A because it has fewer adverse side effects.
The neuraminidase inhibitors. Both agents help prevent both influenza A and B. In one community study, zanamivir protected 30% and oseltamivir 50% of the population for contracting influenza. Protection rates have been even higher in families and nursing home patients exposed to the flu.

Potentially these agents could be used for prevention in the following cases:

In combination with the flu vaccine during seasons where there is a poor match between the virus and vaccine.
During two-week periods after a vaccination when antibodies are developing and the individual is still vulnerable to the virus.
As supplementary protection for vaccinated people in high-risk groups, such as the elderly or people with compromised immune systems.
In people who cannot have vaccinations for whatever reason.
For people who prefer an antiviral agent to a vaccine.

To date both M2 inhibitors and oseltamivir have been approved for prevention of influenza.

Viral Influenza Vaccines

Description of Vaccines. Vaccines are designed to recognize foreign agents (called antigens) in the body and to attack them. Vaccines against influenza currently employ inactivated (not live) viruses to produce an immune response that will then attack the active virus. Vaccines are given by injection in the fall, usually between October and December. A live but weakened intranasal vaccine (FluMist) should be available soon. It is engineered to grow only in the cooler temperatures of the nasal passages, not in the warmer lungs and lower airways. The vaccine boosts the specific immune factors in the mucous membranes of the nose that fight off the actual viral infections. It is employed using a nasal spray and in one study provided protection against the flu in up to 93% of children.

Annual Redesign. At this time, vaccines must be redesigned each year to match the current strain. This is because both influenza A and B viral strains undergo changes over time (known as antigenic drift or shift), so a vaccine that works one year may not work the next. Influenza A is a particular problem because it can infect other species, such as pigs or chickens, and undergo major genetic reassortments. Influenza B viruses tend to be more stable than influenza A viruses, but they too vary.

Candidates for the Vaccine. The following adults should be vaccinated each year:

All adults 50 years and older, and particularly those in nursing homes.
Pregnant women who will be in their second or third trimester during flu season.
Anyone at risk for serious complications, including people with heart disease, lung problems, immune deficiencies, diabetes, kidney disease, or chronic blood disease.
HIV patients.
Health care workers, nursing home employees, and other who may expose high-risk people to the flu.

The following children over six months should be vaccinated against influenza:

Any child with a condition that requires regular medical care.
Any child who has been hospitalized for a serious illness (particularly lung, kidney, diabetes, sickle-cell, or immune deficiencies.)
Children who are receiving long-term aspirin therapy should also be immunized against the flu because they are at higher risk for Reye's syndrome, a life-threatening disease, if they get the flu.

The vaccine may be useful or important in other individuals as well:

People such as firemen or policemen who are critical for public safety.
People at risk for complications of influenza and who are traveling to the tropics at any time or to the Southern Hemisphere between April and September.

The vaccines may be slightly less effective in the elderly, the very young, and patients with certain chronic diseases than in healthy young adults.

Effectiveness and Benefits. The vaccinations protect against influenza in between 70% and 100% of healthy adults when the virus and the vaccine are well matched.

In the absence of a match and among the elderly and children, they are protective in 30% to 60% of people. Even in people with a weaker response, however, the vaccine is usually protective against serious flu complications, particularly pneumonia, if such people get the flu.

Vaccinated older adults have lower hospitalization rates and death from any cause than unvaccinated peers.

Additionally, studies are finding that the more people that are vaccinated, the healthier the community at large. One interesting study in Japan found that vaccinating children actually helps protect the elderly.

Negative Effects. Possible negative responses include the following:

Newer vaccines contain very little egg protein, but an allergic reaction still may occur in people with strong allergies to eggs.
Almost a third of people who receive the influenza vaccine develop redness or soreness at the injection site for one or two days afterward.
Other side effects include mild fatigue and muscle aches and pains; they tend to occur between six and 12 hours after the vaccination and last up to two days. It should be noted that these symptoms are not influenza itself but an immune response to the virus proteins in the vaccine. Anyone with a fever, however, should not be vaccinated until the ailment has subsided.
Some studies have reported more severe asthma symptoms in children with the lung condition. A 2000 study of asthmatic children, however, reported no increased risk. In fact, there was some indication that the vaccination helped reduce asthma attacks over time. More research is needed to confirm or refute these results.

Pneumococcal Vaccines

Experts are now recommending that more people, including healthy elderly people, be given the pneumococcal vaccine, particularly in light of the increase in antibiotic-resistant bacteria. This vaccine does not prevent influenza, but it may help prevent pneumonia in people who are susceptible to sever flus.

Candidates for the Pneumococcal Vaccine. A recently approved pneumococcal vaccine (Prevenar or PCV7) is very effective in children, and some experts believe that universal vaccinations for infants would prevent a million cases of ear infections as well as serious infections, such as pneumonia. In one study, a similar vaccine under investigation protected not only children in day care from serious respiratory infections, but their younger unvaccinated siblings had fewer infections as well.

The pneumococcal vaccine is now recommended by many experts for the following groups:

All children up to age two and certain high-risk children up to age five, such as those at risk for meningitis or widespread infection.
All elderly people.

Special high-risk groups are strongly advised to have pneumococcal vaccinations:

Adults or children who have immune deficiencies (eg, HIV) or are undergoing treatments to suppress the immune system.
Children with sickle-cell disease.
Patients with kidney disease or kidney transplants. Older people who have had transplant operations or those with kidney disease may require a revaccination after six years.
Patients with problems in the spleen.
Alcoholics (especially those with cirrhosis).
Adults or children with any condition that increases the risk for pneumonia. (Those at risk for serious pneumonia should be revaccinated six years after the first dose.)

Protection lasts for over six years in most people, although the protective value may be lost at a faster rate in elderly people than in younger adults.

HOW ARE SYMPTOMS OF COLDS AND MILD FLU TREATED?

Home remedies

The following remedies will not cure a cold but may help a person endure it:

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.
Chicken soup does indeed help congestion and achiness. 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.

Nasal Strips

Nasal strips (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 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 home-made 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. Some physicians, however, argue for the effectiveness of a traditional nasal wash, used for centuries, that uses no baking soda and more fluid for each dose and less salt than the saline washes in the study. The process is something like this:

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.
Blow the nose gently.

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.
A nasal wash should be performed several times a day.

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 six to 12 hours. Ingredients are the following:

Oxymetazoline: Brands include Vicks Sinex (12-hour brands), Afrin (12-hour brands), Dristan 12-Hour, Good Sense, Nostrilla, Neo-Synephrine 12-Hour).

Short-Acting Nasal-Delivery Decongestants. The effects usually last about four hours.

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 three to five 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 to 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 three 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. Common active ingredients include:

Pseudoephedrine: Sudafed, Actifed, Drixoral. Nearly every decongestant and combination remedy now contains pseudoephedrine, since the alternative decongestant, phenylpropanolamine (PPA) was been taken off the market [see below]. Some oral decongestants, such as Nature's Way and others, contain naturally-derived pseudoephedrine from the Chinese herb ephedra. Side effects still apply to these products as well.
Phenylpropanolamine (PPA). PPA was a common ingredient in many decongestants, but has been withdrawn from the US market. [ See Warning Box, Decongestants and Phenylpropanolamine.]

Side Effects of Decongestants

Certain adverse effects 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.

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. (Oral medications with pseudoephedrine have less of an effect on blood pressure than those containing phenylpropanolamine, but both should be avoided by anyone with high blood pressure.)
Thyroid disease.
Diabetes.
Prostate problems that cause urinary difficulties.
Migraines.
Raynaud's phenomenon.
High sensitivity to cold.
Emphysema or chronic bronchitis. (Such individuals should particularly avoid high-potency short-acting nasal decongestants.)

Anyone with these conditions should not use either oral or nasal decongestants without a doctor's guidance. Other people 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.

Warning Box: Decongestants and Phenylpropanolamine (PPA)

In response to reports of an increased risk of stroke in young women who took products, including oral decongestants, containing phenylpropanolamine (PPA), the Food and Drug Administration (FDA) began taking action to ban it from the US market in November of 2000.

Many agents contained this product. Nearly all, however, have now been withdrawn from the market or reformulated. A number of brands that previously contained PPA have now substituted other active ingredients (usually pseudoephedrine) and are safe to use. They include but are not limited to the following:

Alka-Seltzer Plus Cold Medicine.
Coricidin D Cold, Flu and Sinus Tablets.
Dimetapp DM, Dimetapp Elixer.
Robitussin CF.
Contac Day/Night Allergy & Sinus.
All Triaminic products.

Anyone with old forms of these medications or any decongestant should check the labels and discard them if they contain phenylpropanolamine.

It should be noted that the incidence of stroke tended to occur in people who took diet suppressants containing PPA rather than decongestants with the ingredient. In any case, serious events were still very rare. Furthermore PPA has been used in dozens of medications for over 50 years. Extreme concern, therefore, is unwarranted.

Combination Cold and Flu Remedies

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. Although one study has indicated that older so-called first-generation antihistamines may reduce cold symptoms, experts postulate 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 (Claritan, Allegra, Zyrtec) do not have these effects and also appear to have no benefits against colds.

In any case, people with bacterial infections in the nasal or sinus passages should not use antihistamines. Antihistamines thicken mucus secretions and can actually worsen bacterial infections. [For more information, see the Report, Allergic Rhinitis (Hay Fever and Rose Fever) and Other Chronic Rhinitis Disorders. ]

Cough Remedies

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 thick phlegm, patients may try cough medications that contain guaifenesin (Robitussin, Scot-Tussin Expectorant), which loosens mucus.
For patients with a dry cough, a suppressant may be useful, such as one that contains dextromethorphan (Drixoral Cough, Robitussin Maximum Strength Cough Suppressant). Well-conducted studies have reported that products containing both dexbrompheniramine and pseudoephedrine (Drixoral) have reduced coughs related to colds.
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.

Remedies for Sore Throat Associated with Colds

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 (Vicks Chloraseptic) may be particularly helpful. Phenol has anti-bacterial 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. None were taking antibiotics.
Cough drops that contain menthol and mild anesthetics, such as benzocaine, hexylrescorincol, phenol, and dyclonine (the most potent), may soothe 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.

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) is the pain-reliever of choice in children. Most pediatricians advise such medications for children who run fevers over 101 degrees 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's Syndrome, a very serious condition, has been associated with aspirin use in children who have flu symptoms or chicken pox.

It should be noted that 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.)

Warnings on Antibiotic Over-Use and Resistant Bacteria

Of great concern is the emergence of common bacteria strains that are now resistant to many standard antibiotics. Among the bacteria are those that cause serious repiratory infections, including pneumonia. Although new powerful antibiotics continue to designed, they are expensive and are also prone to resistance eventually.

Over-Use of Antibiotics. One of the primary causes of the increase in resistant bacteria is the world-wide overuse of antibiotics. Each year in the United States alone 160 million prescriptions are written for antibiotics equal to about 25,000 tons of these drugs. About half are used for patients and half animal, fish, and other agricultural uses.

Virtually no antibiotics for colds are necessary, even with persistent cough and thick, green mucus, unless there is evidence of an accompanying infection. In one disturbing study, antibiotics were prescribed for nearly half of children who went to the doctor for a common cold. And experts estimate that, outside the hospital setting, only half of the antibiotics currently being prescribed for sore throat and 20% of prescriptions for persistent coughing are necessary.

Antibiotics may be required for upper respiratory tract infections only under certain situations, such as the following:

In patients, particularly small children or the elderly, who have medical conditions that put them at high risk for complications from such infections.
In strep throat (which is caused by the Streptococcal bacteria). (Strep throat makes up only about 12% of all sore throat cases.)
In some cases of an accompanying sinusitis, ear, or other bacterial infection. [See the Reports Ear Infections (Otitis Media) in Children and Sinusitis.]

Resistant Bacterial. Prescribing antibiotics to so many people who do not require antibiotics is raising great concern among health professionals because of emerging strains of bacteria that are no longer eliminated using many standard antibiotics. Although new powerful antibiotics continue to be designed,