Anti-allergic drugs are mainly antihistamines. The main adverse reactions of the first generation antihistamines are: sedation, drowsiness, general weakness, dizziness, and inability to concentrate. A few drugs can also cause tachycardia, mydriasis, dry mucous membranes, difficulty urinating, gastrointestinal tract reaction, liver and kidney function damage, anemia, etc. Therefore, the following matters should be paid attention to when using this kind of medicine: ① It is prohibited or used with caution by high-altitude workers, drivers, and machine operators. ② Do not use excessive doses of these drugs, otherwise symptoms of central nervous system depression may occur. Try to avoid using them at the same time as compound cold preparations, because many compound cold preparations contain antihistamines such as chlorpheniramine. ③ Avoid using it with drinks that have inhibitory effects on the central nervous system (such as alcohol), sedative-hypnotic anticonvulsants (such as diazepam), and antipsychotic drugs (such as chlorpromazine), otherwise it may cause dizziness, general weakness, Symptoms of excessive central nervous system suppression such as movement disorders, blurred vision, and diplopia. Children, adults, and frail patients are more likely to occur. ④ Avoid using it with anticholinergics (such as atropine) and tricyclic antidepressants (such as amitriptyline), otherwise side effects such as thirst, constipation, difficulty urinating, bradycardia, aggravation of glaucoma symptoms, and memory dysfunction may occur. ⑤ Patients with glaucoma should avoid taking diphenhydramine, cyproheptadine, promethazine, and doxepin. ⑥ Patients with prostatic hyperplasia and pyloric obstruction should use cysteine ??and diphenhydramine with caution; patients with liver and kidney dysfunction should use promethazine with caution. ⑦Pregnant women and children should not use doxepin, dechlorhydrizine, Atarax, and Naoyizin, etc. ⑧ Diphenhydramine is prohibited for neonates, premature infants, pregnant women and lactating women. ⑨ The elderly and patients with heart disease should use doxepin, promethazine, and Atarax with caution, and Naoyizin should be used instead. Pediatric patients can choose safer chlorpheniramine and diphenhydramine. The main adverse reactions of second-generation antihistamines include: prolongation of the QT interval in the patient's electrocardiogram, different types of arrhythmias such as supraventricular tachycardia and cardiac arrest, and in severe cases, sudden cardiac death. Especially terfenadine and astemizole have been reported the most. The cardiotoxicity of most antihistamines is related to improper compatibility, blindly increasing the dose, and patients with heart disease. According to reports, since the 1990s, there have been reports of syncope and torsade de pointes caused by some specific second-generation antihistamines (terfenadine, astemizole) around the world. . From 1986 to 1996, the World Health Organization (WHO) analyzed the side effects of second-generation antihistamines in 17 countries and found that 106 patients developed different types of arrhythmias when loratadine was used, and 13 cases Sudden death occurred; 19 cases of cetirizine had arrhythmia and two cases of sudden death. In addition, there are side effects such as dry mouth, fatigue, gastrointestinal discomfort, headache, hypotension, anxiety, depression, white blood cell count, blood sugar and electrolyte abnormalities. Some drugs can cause mild drowsiness, drowsiness, and dizziness. In view of the cardiotoxicity of second-generation antihistamines, it is particularly important to use second-generation antihistamines rationally to avoid the occurrence of cardiotoxicity. Therefore, clinicians must keep the following precautions in mind when using this type of drug: ① It is prohibited to mix with macrolide antibiotics (such as erythromycin, azithromycin, roxithromycin, clarithromycin), imidazole antifungal drugs (such as ketone Conazole, itraconazole, fluconazole), otherwise the blood concentration of second-generation antihistamines may increase, causing ventricular arrhythmia or even sudden death. The two drugs should be used together with erythromycin or ketoconazole. There have been more than 100 cases of sudden death caused by taking them. The above-mentioned types of drugs are widely used in clinical applications and deserve the attention of clinicians. ②Patients with heart disease should avoid use. These diseases themselves can prolong the QT interval and form various arrhythmias. The use of second-generation antihistamines will increase the risk of arrhythmias induced by these drugs. ③ Avoid use in patients with electrolyte disorders (such as hypokalemia, hypocalcemia, hypomagnesemia, etc.). Electrolyte disorders can affect the depolarization of ventricular myocardium, resulting in prolongation of the QT interval on the electrocardiogram. Avoid use with antiarrhythmic drugs (such as quinidine, clocainide), calcium antagonists (such as prenilamine), sedative-hypnotics (such as chloral hydrate), etc. ⑤ Try not to exceed the recommended dose of this type of drug. People with severe illness can use different types of antihistamines in combination to improve the efficacy. To prevent the occurrence of drug resistance, antihistamines can be used interchangeably. ⑥ When high-altitude workers, drivers, and machinery operators have to use antihistamines, they should choose loratadine and desloratadine, because some patients still have varying degrees of sedation and sedation after using other second-generation antihistamines. Drowsiness effect.

① Children over two years old can use loratadine, desloratadine, cetirizine, and levocetirizine; children under 12 years old should use mizolastine, ebastine and other drugs with caution. ⑧ Second-generation antihistamines are prohibited for pregnant and lactating women. ⑨ Patients with prostatic hypertrophy and pyloric obstruction should use mequitazidine with caution. ⑩ Mizolastine is generally not to be taken at the same time as cimetidine, cyclosporine, and dixin. This may be a side effect of your medication.