Although many people have experienced colds, there are still many misconceptions. And these misconceptions directly and wrongly guide our treatment behavior, making many people suffer a lot from the common illness of cold. Cold is a common infectious disease of the upper respiratory tract, mainly caused by viruses, which can be followed by bacterial infections. In general, it is divided into common cold and influenza. Only a clear understanding of the type and characteristics of the cold can be treated symptomatically. The survey shows that more than 90% of people think that cold is a minor problem and can be cured by buying some cold medicine, but in fact, there are also rules for buying cold medicine. The main symptoms of common cold are dry, itchy or burning sensation in the throat, nasal congestion, sneezing, runny nose, sore throat, cough, low fever, mild chills, headache and other symptoms. It is mainly spread by droplets containing the virus, but can also be transmitted by contaminated hands and utensils. There are a variety of cold medicines on the market, most of them are compound preparations, many cold medicines have different names, but the ingredients are the same or similar, but have their own characteristics and indications, and should be used according to their characteristics of symptomatic medicine. Selection of the main four principles: 1, according to the symptoms to choose: fever and headache patients should choose anti-cold medicine containing antipyretic and analgesic ingredients; nasal congestion, runny cold patients should choose anti-cold medicine containing antihistamine ingredients and vasoconstrictor ingredients; cough symptoms heavier people should choose to use anti-cold medicine containing dextromethorphan. 2, according to the work selection: driving a car or boat, working at height, operating precision instruments, avoid using cold medicine containing chlorpheniramine or benadryl, because both have the adverse effect of drowsiness. 3, according to the age of choice: infants and young children are prohibited to contain caffeine and pseudoephedrine cold medicine; elderly people due to liver and kidney function decreases, long-term or high doses of antipyretic analgesics can cause liver and kidney function damage due to drug accumulation. 4, according to their own situation: patients suffering from heart disease, hypertension, hyperthyroidism, glaucoma, prostatic hyperplasia and sensitive to sympathomimetic drugs should be cautious with preparations containing pseudoephedrine hydrochloride; chronic bronchitis and pneumonia patients should be cautious with drugs containing dextromethorphan, because its cough suppressant effect can affect the elimination of sputum leading to respiratory obstruction. After suffering from a cold, if you buy drugs in the pharmacy on your own, it is best to follow the above four principles to buy against.