Signs and Symptoms

If you have been infected with the flu, you will usually begin to feel the symptoms one to four days later. It is important to note that you are contagious and can spread the flu to others before your symptoms start and for another three to four days after your symptoms appear. The symptoms can start very quickly and may include:

Headache
Chills
Dry cough
Body aches
Fever
Stuffy nose
Sore throat

Typically, the fever begins to decline on the second or third day of the illness. The flu almost never causes symptoms in the stomach and intestines. The illness that people often call "stomach flu" is not influenza.

Flu symptoms in school-age children and adolescents are similar to those in adults. Children tend to have higher temperatures than adults, ranging from 103 degrees to 105 degrees. Flu in preschool children and infants is hard to pinpoint, since its symptoms are so similar to infections caused by other viruses.