With North American Influenza A outbreaks in many countries around the world, it is important for people to maintain good hygiene habits and take adequate precautions, and many people also have plenty of over-the-counter cold and flu remedies at home. Taking cold medicine is by no means a means of prevention, but rather a measure for symptomatic treatment during a cold, and three key points must be mastered when using it, i.e., analyzing the ingredients, judging the symptoms, and prescribing the right medicine for the symptom. Colds are caused by viruses, and regardless of the type of cold, the symptoms are nothing more than fever, runny nose, cough, nasal congestion, headache and so on. Commonly used medicines for cold symptoms include: Anti-allergy medicines: they can relieve the symptoms of sneezing, nasal congestion and runny nose, and at the same time, they have a slight sedative effect, such as chlorpheniramine (paracetamol) and diphenhydramine. Reduce nasal mucosal congestion drugs: can selectively contract the blood vessels of the nasal mucosa, reduce the symptoms of nasal congestion, so as to reduce nasal discharge, such as phenylpropanolamine, pseudoephedrine and so on. Antipyretic and analgesic drugs: can reduce fever, relieve headache, joints and general muscle pain and other symptoms, such as aspirin, acetaminophen, diclofenac and so on. Most of the compound cold medicines on the market nowadays contain the above ingredients, which can reduce the symptoms of cold and flu. In China, the approved cold and flu medicines on the market are proven to be safe and effective after years of clinical testing, such as White Plus Black, etc., and can be used without fear by those who have obvious cold and flu symptoms. Before choosing the first to determine what kind of symptoms caused by colds; secondly, when choosing between different cold medicines to treat the symptoms, you can consult the pharmacist in the pharmacy; again, carefully read the instructions for use of the drug, especially need to understand the drug does not apply to the crowd, possible adverse reactions, etc., so that when you feel uncomfortable no longer continue to blindly take; finally, children, pregnant women and the elderly may be because of special physical conditions Finally, children, pregnant women and the elderly may have special medical conditions that require them to consult a physician or pharmacist when choosing over-the-counter cold medicines. As long as it is a medicine, it may produce different degrees of adverse reactions to the human body, and different people have different adverse reactions to medicines. Dizziness, nausea, discomfort and other symptoms after taking the drug are mild adverse reactions, which are relatively common, and patients should consult their physicians about their symptoms without being overly nervous.