What Causes a Cold or the Flu?
What Exactly Is a Cold?
Every one of the 1 billion annual cases of the common cold in the United States begins when a tiny dose of a virus is inhaled into the nasal passages from droplets sneezed or coughed into the air or transmitted by contaminated fingers. The virus then moves to the back of the nose, where it attaches itself to the adenoid area and begins to reproduce. Within 10 to 12 hours, the body attempts to defend itself by releasing mucous-gland secretions and by sneezing and coughing―the cold symptoms you begin to feel. Typically, symptoms worsen over the first 48 hours, then start to diminish. Most colds last about one week, though a severe case may linger a bit longer.
What Exactly Is the Flu?
If a cold is like being sideswiped by a bike messenger, the flu is like being run over by a truck. Caused by the influenza virus, it comes on more suddenly than a cold, and the symptoms, which usually last four to five days, are generally worse. Your fever can be moderate to high―usually 101 to 103 degrees. Body aches and fatigue may be more intense, and your cough will be dry and hacking rather than wet. You’re more likely to have a headache and chills and less likely to get a sore throat or a runny nose. Because the flu invades the bronchial tubes and the lungs, it’s more serious than a cold.
How You Catch Them
It’s more accurate to say that the flu or a cold virus catches you. Both are spread in the same two ways. An infected person coughs or sneezes, shooting virus particles into the air, which you breathe in. Or you touch an object―a doorknob, someone’s telephone―contaminated with the virus and then carry it to your nose or tear ducts with your fingers.
How to Manage a Cold
Make yourself comfortable. “That means listening to your body,” says Eric Westerman, M.D., an infectious-disease specialist at the Methodist Hospital, in Houston. “If your body says you need to sleep, then that’s what you should do. Ignore it and it could take you longer to recover.
Drink three to four extra glasses of fluid a day to replace the moisture lost from coughing and sneezing and to thin mucous secretions.
Try echinacea. A recent study of 14 controlled trials found the herbal supplement can slightly reduce a cold’s duration―and can cut people’s risk of catching a cold by 35 percent when a rhinovirus, the most common cold culprit, is involved.
Rely on vitamin C. A 2007 review of 30 studies found it doesn’t reduce your chances of getting a cold and is unlikely to affect an existing cold’s severity.
Use zinc to calm a cough. Guidelines set forth by the American College of Chest Physicians in 2006 do not recommend turning to it for this purpose.
OD on Airborne. Kelly Scolaro, Pharm.D., who cowrote the 15th edition of the Handbook of Nonprescription Drugs ($150, amazon.com), says there is “absolutely no clinical evidence out there about the effectiveness or the safety of this product.” And as there are 5,000 international units (IU) of vitamin A in each tablet, people who take Airborne can easily exceed 10,000 IU, the maximum safe daily dose for this vitamin.
How to Manage the Flu
Taking a prescription drug, such as Tamiflu or Relenza, can reduce the duration and severity of the flu, but these drugs must be started within 48 hours of the onset of symptoms. Most symptoms will disappear by themselves within a week, though a cough and fatigue could persist for a few weeks.
Stay hydrated, get lots of rest, and try appropriate over-the-counter or home remedies. (See Your Cold and Flu Symptoms, Explained.)
When a Cold or the Flu Lingers
If your cold symptoms haven’t gotten better―or are worse―after 10 to 14 days, you may have a sinus infection or bacterial bronchitis. This means that bacteria have caused irritation to the main airways of the lungs. Call your doctor; these infections usually require antibiotics.
The worst complication from the flu is bacterial pneumonia. This primarily strikes older adults and those with chronic heart or lung conditions, but healthy people can also get it. Call your doctor if your symptoms disappear and then return or if you have chest pain, shortness of breath, or a severe cough that brings up blood or phlegm.
Your Prevention Plan
"Hand washing is number one, two, and three on any list of ways to prevent infection,” says Susan Rehm, M.D., medical director of the National Foundation for Infectious Diseases. Scrub for at least 20 seconds with soapy water. When you have no sink, an alcohol-based antibacterial hand gel (like Purell) can help. Enough sleep, a balanced diet, and regular exercise can also help make you less vulnerable.
To avoid the flu, get vaccinated. The vaccines may thwart 70 to 90 percent of flu cases, and even if a strain slips through, your illness should be milder. Schedule a vaccine in September or October, well before the peak of the flu season.
If your family members are sick will you get sick, too? With a cold, you’re most contagious two to three days after the first symptoms appear. You can pass the flu along one day before symptoms develop and up to five days after becoming sick.