A severe cold is generally a cold with more severe upper respiratory tract symptoms and systemic symptoms, and may also be followed by related complications. Upper respiratory tract symptoms are mostly caused by viruses and other pathogenic microorganisms invading the human respiratory tract, causing inflammatory reaction in the respiratory tract, which in turn causes symptoms such as runny nose, headache, sneezing, sore throat, etc.; systemic symptoms such as fever are also more serious. The symptoms of severe cold are more serious, which will cause a series of complications and affect the human body’s health. For example, the combination of bacterial respiratory tract infection after cold causes acute tonsillitis and other diseases. Unlike common colds, severe colds not only have more serious symptoms than normal colds, but also last for a longer period of time, so it is important to consult a doctor in time when you have a severe cold.