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Colds (common colds) and the flu (influenza) are contagious infections that affect the respiratory system. Both are airborne illnesses, spread through coughing and sneezing. Colds typically are confined to the upper respiratory system—the nose and throat—but the flu affects the lungs and in severe cases may cause death, especially in senior citizens, young children, and those with a compromised immune system.
Both the common cold and the flu are typically caused by viruses. According to the Mayo Clinic, there are over 100 viruses that can cause cold symptoms (Mayo Clinic, 2013).
There are also many different viruses that can cause the flu. According to the World Health Organization, the medical community combines the three most common viruses (A, B, and C) under the heading of seasonal influenza. Type A influenza has several subtypes or strains, and is believed to be the most dangerous of the three viruses that cause flu. Researchers believe that strains of type A influenza were responsible for the global outbreaks of flu in 1918, 1957, and 1968 (WHO, 2009).
Symptoms of the common cold are unpleasant, but not usually dangerous. Beginning two to three weeks after infection, they include
Adults usually don’t run temperatures when they have a cold, but children can run temperatures of up to 102 degrees.
The symptoms of the common cold usually last anywhere from 48 hours to 14 days. Most people recuperate fully within 10 days.
The flu has many symptoms in common with a cold, but there are some significant differences as well. Symptoms found in both cold and flu may include:
Symptoms that set the flu apart from a common cold include:
Most people with colds do not go to the doctor. When they do, the doctor usually makes his or her diagnosis based on the patient’s description of symptoms. Occasionally, the doctor might order a test like a throat culture to rule out a more serious condition like strep throat.
According to the Centers for Disease Control and Prevention, the flu can likewise be diagnosed by a description of symptoms, but there are times when a doctor may want to do certain laboratory tests to identify the strain of flu involved. Tests are more effective if performed within four days of the onset of symptoms (CDC, 2009).
Testing is generally performed by swabbing the patient’s nose or throat for secretions. In cases where the patient is coughing up phlegm, sputum may be tested as well.
Rapid influenza tests can give doctors results in less than 15 minutes, but these tests tend to have a high rate of false negatives—that is, the test says the person does not have influenza when in fact he or she does.
The other kind of test, a viral culture, involves sending the swab to a lab. The results are not available for three to 10 days, but viral cultures can give a doctor very specific information about the exact type and strain of the influenza virus involved (CDC, 2009).
There is no cure for the common cold, but there are medications that may make the symptoms a little more bearable. These include over-the-counter pain and fever relievers, nasal sprays to ease congestions, and cough medications. If you have several medical conditions, take prescription medications, or are planning treatment for a young child, check with your doctor or pharmacist before taking over-the-counter medications.
There are also some things you can do at home that will help you feel better. These include drinking lots of water to stay hydrated, getting as much rest as possible, using a humidifier to moisten the air and make breathing easier, and relieving throat pain with salt water gargles.
These same interventions can also help ease symptoms of the flu. Most adults do not require medical intervention and recover from the flu within three to five days. According to the Minnesota Department of Health, you should seek medical attention if you meet any of the following criteria:
In cases like these, your doctor might prescribe a type of medicine known as an antiviral. The two antivirals most commonly used to treat influenza are oseltamivir (Tamiflu) and zanamivir (Relenza). You take oseltamivir by mouth and zanamivir by inhaler. Zanamivir is not recommended for anyone with pre-existing respiratory problems.
Both colds and the flu can make you feel absolutely miserable, but they generally fade away on their own after a few days.
There are, however, a few complications to look out for. In children, colds can lead to painful ear infections. They may also cause wheezing and trouble breathing in children with asthma. In both children and adults, there is a possibility that a cold may lead to a sinus infection or another type of secondary infection. These infections are often bacterial and need to be evaluated and treated by a doctor.
Flu is most dangerous in young children (under the age of two) and older adults (over the age of 65). These populations are vulnerable to complications including bronchitis, sinus infections, ear infections, and pneumonia. Pneumonia is the most serious outcome and can lead to death.
The best prevention for both colds and flu is good hygiene. Be sure to wash your hands carefully and often. It also helps to keep your home and appliances clean and as germ-free as possible.
If you have a runny nose or are coughing and sneezing, carry a stash of tissues around with you. Discard a tissue after you blow your nose, cough, or sneeze into it. If you feel a sneeze coming and don’t have a tissue available, sneeze into the crook of your arm. This helps keep your hands clean.
Stay away from people who exhibit signs of a cold or the flu. During flu season (October through May), try to stay away from large crowds of people.
Get an annual flu vaccine. The vaccine will protect you against the three viruses that are most likely to cause influenza during the coming season. If you’re not fond of shots, you may be eligible to get your vaccination as a nasal spray.
Written by: Debra Stang
Medically reviewed on: May 08, 2013: George Krucik, MD, MBA
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