The symptoms of flu might look extremely common at first, for instance, running nose, cold, and cough. The development of flu takes place gradually in a person and makes one feel worse when compared to cold. The symptoms of flu develop in 2-3 days, and if a person is healthy with a strong immune system it will hardly take 4-5 days to cure t=influenza. A person suffering from medical issues might take a long time to cure influenza approximately a week or two.