Sixteen considerations for choosing antihistamines: 1. Is it a histamine-mediated allergic disease? Is there an indication? 2. What is the urgency of the disease? Use those with rapid onset of action and short half-life for acute conditions. 3. What is the planned course of treatment? Long-term use of certain antihistamines can lead to weight gain. 4.What kind of work do you do? Is it dangerous work, fine work, mental work, driving or not? 5. Is there any heart disease? Is the electrocardiogram normal? Is there any heart rhythm disorder, is QT prolonged? 6. Is there any electrolyte disorder? Is there hypokalemia? 7. Is liver function normal? Are the drugs used metabolized in the liver? 8. Is renal function normal? Is the drug excreted in the urine? 9.Whether other diseases (such as closed angle glaucoma, benign prostate hyperplasia) are combined? 10.Is there any combination of asthma? Is the sputum sticky and not easy to cough up? 11.Are macrolide antibiotics (e.g. erythromycin) and azole antifungal drugs (e.g. ketoconazole) being used for other diseases? 12. Is there any history of drug allergy? Can there be cross-allergic reactions to antihistamines of the same chemical structure? 13.Is it pregnancy (month)? 14.Is it the time of breastfeeding? Is the drug used easy to pass the blood-milk barrier? Is it easily excreted from breast milk? 15.Is it necessary to do skin test for allergen diagnosis? Is a drug allergy test (e.g. penicillin skin test) required? If antihistamines are being applied, four half-lives are needed to stop the drug. 16. Cost-effectiveness and affordability of the patient?