Influenza, also known as flu, is a viral infection of the upper respiratory tract (nose and throat) and the lung, caused by influenza virus. Symptoms include sore throat, cough, runny nose, congestion, and sneezing and chest tightness. There may be high-grade fever. The cough is usually singular, non-productive cough (no sputum). The symptoms can be treated with home remedy and improved in one or two weeks. If they last more than two weeks, or there is high-grade fever, repetitive or productive coughs, or severe muscle pain, please go to see your doctor for diagnosis and treatment.
Difference between a cold and flu: They share the very similar symptoms, but flu is much worse. People with flu usually have high-grade fever, chest tightness, body/muscle aches, and fatigue. Since flu can infect the lung, the complications of the flu are serious, including pneumonia, sinus infections, and asthma. Therefore, people (the young, the elderly, with chronic health problems) who are at high risk of developing these complication should go to see their doctors if there are the symptoms of flu.