The most common symptoms of the disease are chills, fever, sore throat, muscle pains, severe headache,coughing, weakness/fatigue and general discomfort.Sore throat, fever and coughs are the most frequent symptoms. In more serious cases, influenza causes pneumonia, which can be fatal, particularly for the young and the elderly. Although it is often confused with other influenza-like illnesses, especially the common cold, influenza is a more severe disease than the common cold and is caused by a different type of virus.