Influenza symptoms can include fever, headache, muscle pain, runny nose, sore throat, extreme tiredness, and cough. Although colds and other viruses may cause similar symptoms, those due to the influenza virus tend to be worse.
Symptoms can begin about one to four days (on average two days) after a person is first exposed to the influenza virus. Fever and other symptoms can usually last 7 to 10 days, with the cough and weakness lasting up to two more weeks.
In children, gastrointestinal symptoms such as nausea, vomiting and diarrhea may accompany the respiratory phase