Symptoms begin suddenly and include fever, headache, extreme fatigue, cough, sore throat, runny or stuffy nose, body aches and sometimes diarrhea or vomiting.

It spreads in respiratory droplets through coughs and sneezes.
Flu is contagious for one day prior to symptoms and up to five days after onset of illness.
Flu and the common cold are respiratory illnesses, but are caused by different viruses; the flu is more intense.

Your doctor can diagnose the flu within the first 2-3 days.

If diagnosed early, your doctor can treat you with an anti-viral medication, which may reduce the severity and length of illness.

Influenza can lead to serious complications: pneumonia or bacterial infections, requiring hospitalization. Each year about 200,000 Americans contract the flu and 36,000 people die from flu complications.

Prevention measures include injected vaccines and nasal-sprays (for certain age groups only.)
Wash your hands with soap often for at least 30 seconds under running water, especially after coughing or sneezing.
Do not rub your eyes—the eye is a perfect portal for colds and flu viruses.

For more information on influenza, visit Centers for Disease Control and Prevention.