Catching a cold - or even worse, the flu - is common this time of the year when close contact with others, busy schedules and stress make us even more susceptible to the many respiratory viruses circulating. But differentiating between a cold and influenza, at least initially, is not always easy.
That's because the two can share a number of the same symptoms, including a runny or stuffy nose, sore throat and cough, says emergency medicine specialist Hans House of the University of Iowa Carver College of Medicine.
Where they differ is in severity, says House, a board member with the American College of Emergency Physicians. Colds tend to be relatively mild and typically last only a few days, he says, "and you can usually still function with a cold.
"When you have that high fever (102 degrees or more), and your whole body aches, and you can't even get off the couch because you're so miserable, that's probably the flu."
Unlike colds, which tend to have a more gradual onset, the flu usually comes on more suddenly, adds Susan Rehm, medical director of the non-profit National Foundation for Infectious Diseases. That characteristic is one feature in the mnemonic device that she recommends for identifying the flu - FACTS ( fever, aches, chills, tiredness and sudden onset).
According to the Centers for Disease Control and Prevention, seasonal flu activity in the USA can begin as early as October and last as late as May, but it usually peaks in January or February.
Common colds, caused by many different viruses but very often rhinoviruses, total about 1 billion cases annually, says the CDC. The flu accounts for fewer cases - the agency says there were about 31.8 million influenza-associated illnesses and 14.4 million-related doctor visits during last year's flu season - but it's considered a far more severe viral infection.
"We know that about 200,000 people are hospitalized each year for flu," says Rehm, also vice chairman of the Department of Infectious Diseases at the Cleveland Clinic. "Complications can include bacterial pneumonia, a weakened heart muscle, and even the death of (otherwise healthy) people."
During last year's "relatively severe" flu season, there were 169 flu-related deaths among children, CDC reported last month. The agency does not keep similar statistics on adults, but estimates that about 24,000 people die each year from influenza.
Because both the common cold and flu are caused by viruses, "neither respond to antibiotics, which only work on bacterial infections," says cardiologist Nieca Goldberg, medical director of the Women's Heart Program at NYU Langone Medical Center.
But many people think otherwise. In a national survey of consumers that the foundation released this month,44% of respondents incorrectly said antibiotics fight the flu and 48% mistakenly believed that flu vaccines "treat" influenza.
Antiviral medications can be prescribed by a physician to treat the flu, says Rehm, "but they work best if given within 48 hours of when people began to feel ill."
The CDC recommends taking "everyday preventative actions" to stop the spread of germs, such as covering your nose and mouth with a tissue when you cough or sneeze; staying home when sick and washing your hands with soap and water.
But getting a flu vaccine (either injection or nasal spray) is key to reducing the risk of flu for everyone, the CDC says, especially for people:
• At high risk of developing serious complications (like pneumonia) if they get sick with the flu;
• Who have certain medical conditions including asthma, diabetes and chronic lung disease;
• Who are pregnant;
• Who are younger than age 5 (and especially those younger than 2), and people 65 years and older;
• Who live with or care for others who are at high risk of developing serious complications;
Receiving the vaccine has been shown to reduce the risk of infection by about 60%, and although there's no guarantee, "it does prevent many of the flu viruses (circulating in a given season), and it's better than nothing," Goldberg says.
In cases where vaccinated people still get the flu, "the symptoms may be lesser" than they would have been otherwise because the vaccine has generated an immune response, House says.
Although 66% of people in the foundation's survey said they believe that people should be vaccinated against the flu, only 43% said they were very likely to be vaccinated this flu season.
Many who resist say they think it leads to the flu or it will make them sick, Rehm says. "Once vaccinated, it takes about two weeks for antibodies to form," she says. "So during that time, if they were exposed to influenza, they could get it because the vaccine hasn't had a chance to work. What happens more often is that they may get another circulating virus or cold that they interpret as the flu."
As for the side effects that often follow a flu shot (sore arm, low-grade fever and achiness), that is your body responding to the injection and making the protective antibodies that fight the flu, she says. "When it's possible to protect against an illness that can cause hospitalization or death, it makes no sense to not take the vaccine."
Is it the cold or the flu?
The National Institute of Allergy and Infectious Diseases says differences include these:
• Fever. Rare for a cold, common with flu. Fevers with flu can go over 102 degrees, especially in children, and can persist three or four days.
• Headache. Rare for a cold, common in flu.
• Aches and pains. Mild with a cold, often severe with flu.
• Fatigue. Sometimes occurs with colds, but flu usually starts with a period of exhaustion, with fatigue lasting two or three weeks.
• Sneezing, stuffy nose, sore throat. The most frequent symptoms of a cold also occur sometimes with flu.
• Chest discomfort, cough. Mild to moderate with colds, but can be severe with flu.
Recommended for relief:
Tried-and-true treatment is best for relief of cold and flu symptoms, according to the American College of Emergency Physicians:
• Get plenty of rest.
• Drink lots of fluids, which can thin mucus and prevent dehydration.
• Over-the-counter medication, such as antihistamines, decongestants and pain and fever reducers, can provide temporary relief from symptoms.
• If you're feeling very weak, running a high fever (102 degrees or higher), have trouble breathing or symptoms worsen, contact a medical care provider. The same is true if you suffer from a chronic illness, such as asthma, diabetes or congestive heart failure, which makes you more vulnerable to complications.
Michelle Healy, USA TODAY