What’s the difference between a cold and the flu?
Click each section below to read more about colds and flu, or view all sections at once.
A contagious respiratory illness caused by more than 200 different types of cold viruses.
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A contagious respiratory illness caused by the influenza virus.
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Questions my colleagues and I are asked about colds and seasonal flu.
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What’s the difference between a cold and the flu?
The common cold is caused by a variety of viruses. Many different viruses can cause colds, so there isn’t one vaccine that can protect you from getting sick. If you have a cold, you may have a stuffy nose, a sore throat, a headache, mild body aches, or a low fever. You may also feel tired, and sneeze and cough frequently. There are medicines available over the counter that may help you treat your symptoms. Antibiotics do not kill viruses, so they do not work for colds or flu. Colds usually last 3 to 7 days but sometimes may continue for as long as 2 weeks.
The flu is generally worse than the common cold. A vaccine is available every year to protect against the most common types of seasonal flu. Flu symptoms come on suddenly and may cause a high fever, headaches, extreme tiredness, a dry cough and sore throat, a runny or stuffy nose, and significant muscle aches. Many of the same over-the-counter medicines that can treat symptoms of colds can be effective in treating the flu.
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What’s the latest news on H1N1 flu? Should I worry about H1N1 this coming flu season?
The 2009 H1N1 influenza virus was a significantly different virus from the other flu viruses that had been circulating for the previous 30 to 40 years. A larger number of people got sick from H1N1 flu in 2009, but the severity of the illness was similar to regular flu. In 2010, the H1N1 virus became one of the main flu viruses circulating in the community. Since this virus is now a part of the “regular” group of viruses each season, one part of the flu vaccine now protects against this strain.
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I heard there is a new influenza A strain circulating in 2012. What do we know about it?
The CDC is tracking a new strain of influenza A that has infected a small number of patients in a few states outside of California. Individuals who have been infected with this strain have not gotten very sick. Most people who got Influenza A had contact with swine (pigs), and human-to-human transmission has not been well documented. The CDC and state health departments are carefully tracking this strain. Kaiser Permanente’s infectious disease experts are also monitoring the situation.
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Since I've been sick already, should I still get a flu vaccine?
Yes, you should get a flu vaccine even if you’ve already been sick this year because there is no way to know what sort of flu you had in the past. In fact, you may not have had the flu at all since many different infections cause the same symptoms as the flu (cough, sore throat, and fever). Even if you did have the flu, infection by one strain of influenza virus won’t protect against other strains. For these reasons, everyone over 6 months of age should get a seasonal flu vaccine every year.
