Upper Respiratory Infection
Most colds clear up on their own in a week to ten days, but occasionally a respiratory infection can lead to a more serious illness such as bronchitis, pneumonia, or flu.
It is estimated that healthy adults get an average of 2 respiratory infections per year. Children generally get many moe because their immune systems are immature, and because they have not yet developed immunity to many of the viruses that cause cold. If any adult gets respiratory infections often, it may be a sign that his or her immune system is not working properly.