Usually, you'll need nothing more than bed rest and plenty of fluids to treat the flu. But in some cases, your doctor may prescribe an antiviral medication, such as oseltamivir (Tamiflu) or zanamivir (Relenza).

By avoiding crowds during peak flu season, you reduce your chances of infection.

Age. Seasonal influenza tends to target young children and people over 65. The pandemic H1N1 virus that surfaced in 2009, however, appeared to be most common in teenagers and young adults. Occupation. Health care workers and child care personnel are more likely to have close contact with people infected with influenza. Living conditions. People who live in facilities along with many other residents, such as nursing homes or military barracks, are more likely to develop influenza. Weakened immune system. Cancer treatments, anti-rejection drugs, corticosteroids and HIV/AIDS can weaken your immune system. This can make it easier for you to catch influenza and may also increase your risk of developing complications. Chronic illnesses. Chronic conditions, such as asthma, diabetes or heart problems, may increase your risk of influenza complications. Pregnancy. Pregnant women are more likely to develop influenza complications, particularly in the second and third trimesters.

But colds usually develop slowly, whereas the flu tends to come on suddenly.

Your best defense against influenza is to receive an annual vaccination.

Influenza, more commonly referred to as "flu," impacts people of all ages. 

, vaccination in December or even later is still beneficial because the virus that causes influenza circulates past the new year. The number of influenza cases usually peaks around February, but this peak can come earlier or later (ranging from December to May).