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The climate in autumn is dry, with temperatures fluctuating frequently. Many people experience symptoms such as a blocked nose, itchy eyes, runny nose, and coughing. Most people assume these are caused by a cold due to the cooler weather, often ignoring another possibility: seasonal allergies. Studies have found that 1/3 of people experience allergic reactions at some point in their lives ； 1/5 of school-age children suffer from asthma ； 1/6 of children have suffered from skin diseases related to allergic reactions, especially eczema. The incidence of allergic diseases in our country is as high as 37.3%. With the increasing prevalence of allergies in recent years, the use of anti-allergy drugs has also grown. However, patients also face many problems, such as the medications not being effective or new allergic reactions occurring after taking them. Therefore, knowing how to use antiallergic drugs correctly is very important for people with allergies and those who are prone to them. The development of antihistamines has gone through three phases, and the drugs representative of each phase are still in use today. Chlorpheniramine (Polaramine) was introduced in 1950 and became a representative of the first generation of anti-allergy drugs; it is still widely used as an anti-allergic ingredient in various combination medications to this day. However, this generation of drugs has a significant sedative and drowsy effect, so they cannot be used in patients who require high levels of concentration, such as drivers. In 1988, cetirizine, the representative of second-generation antihistamines, was introduced to the market, marking the beginning of an era of more effective antihistamine treatments. Although these drugs of this generation are widely used, some of them may have cardiac toxicity as side effects; therefore, they should be used with caution in patients with heart disease (especially those with arrhythmias) and those with impaired liver function. It is also important to avoid taking them together with drugs that affect their metabolism. Fexofenadine tablets, which were introduced in 1996, and levocetirizine, introduced in 2002, can be temporarily referred to as third-generation antihistamines. They have been improved through second-generation antihistamines, featuring no cardiac toxicity, stronger antihistamic effects, higher safety, and no drowsiness. There are \"five things to note\" when using medications; anti-allergy drugs cannot be used arbitrarily, and there are five points to keep in mind. First, drugs with no sedative effect are suitable to be used during the day, while drugs with sedative and sleep-inducing effects can be used after dinner or before bedtime. For chronic allergic diseases, due to the relatively long duration of treatment, drugs that do not cause drowsiness and have relatively few other side effects should be chosen. Secondly, long-term use of an antihistamine, especially for more than a month, may lead to a decrease in its effectiveness. For patients whose therapeutic effect gradually diminishes and whose response to treatment is weaker than normal during medication use, it is recommended to switch to another antihistamine with a different mechanism of action as soon as possible; it is best to avoid using drugs of the same type or those with a similar chemical structure. Third, once signs of an allergy are detected, such as sneezing, itchy eyes, or a runny nose, antiallergic drugs should be taken immediately to prevent the condition from worsening. Therefore, anti-allergy medications should be one of the essential medicines at home, especially for those with an allergic constitution who had better carry them with them at all times. Fourth, if, while taking anti-allergy medications, the patient’s condition persists or new allergic symptoms such as itching, rashes, or even shock occur, it is necessary to consider the possibility that the anti-allergy drugs are causing an allergic reaction, and seek medical attention promptly. Fifthly, for chronic, intractable, or severe acute allergic diseases, using two or more antiallergic drugs simultaneously (i.e., combination therapy) can enhance the therapeutic effect. For those who require long-term combination therapy, once the condition is stable and symptoms are under control, all medications should not be discontinued immediately. It is recommended to stop one medication at a time and gradually reduce the use of all medications, in order to reduce the risk of disease recurrence. When administering medication to children, a dosage form suitable for them should be chosen. Compared with the general population, special groups need to be more careful when using anti-allergy drugs. For pregnant and breastfeeding women, there are currently no absolutely safe antihistamine drugs. During pregnancy, loratadine and cetirizine can be chosen after weighing the risks; both of these drugs are classified as Category B during pregnancy. Drugs classified as Categories A and B pose no harm or side effects to the fetus, and can generally be used safely during pregnancy. Fexofenadine tablets, azelastine, and desloratadine are not recommended for use during pregnancy. Under the guidance of a physician, breastfeeding women can take loratadine, cetirizine, and chlorpheniramine in appropriate amounts. For elderly patients with allergies, antihistamines such as fexofenadine tablets and cetirizine are recommended as first-choice treatments. For children with allergies, the preferred choice are second-generation antihistamines in forms suitable for children, such as oral solutions, drops, suspensions, etc. Attention should be paid to age restrictions when using them; the instructions for most second-generation antihistamines state that they can only be used in patients aged two years and above, while cetirizine drops and desloratadine dry suspension can be used in children aged one to two years. (Yao Yao) (Responsible editors: Liang Ruoxin (Shi*Sheng), Xiong Xu)