It is well known that the most common symptom is a runny nose and a feeling of a little cold. How do you know it's just a common cold and not a serious illness? The common cold tends to go away on its own after 3 to 4 days, said Dr. Melisa Lai Becker, Head of Emergency at Cambridge Health Alliance (UK). If symptoms last longer, there may be something more worrying about, such as the flu or mononucleosis. Mononucleosis can cause dangerous swelling of the spleen. So, should go to the doctor immediately.
