Colds can cause colds because when a person is in a cold environment, the body’s immunity is lowered and viruses and bacteria invade the mucous membranes of the respiratory tract, thus causing cold symptoms. Colds are upper respiratory tract infections, caused by viral infections, which are characterized by nasal congestion, runny nose, sore throat and other symptoms, and can be combined with or secondary to bacterial infections. Cold can be cold because when the body is in a low-temperature environment, it needs to consume extra energy to resist the cold, when the peripheral blood vessels contract, resulting in a decrease in the blood supply to the nasal mucosa, the body’s metabolism and immune activity slows down, the viruses and bacteria are easy to invade the mucosa of the respiratory tract, which can lead to cold symptoms. Colds are self-limiting and usually heal in a week or so. If the symptoms are more severe or fever occurs, it is recommended to consult a doctor in time and take the appropriate treatment plan under the doctor’s guidance.