Long-term use of anti-allergy drugs may cause side effects such as drowsiness, dry mouth, glaucoma, liver and kidney damage. Drowsiness: Drowsiness is the most common side effect of anti-allergy drugs, especially the first generation antihistamines such as chlorpheniramine and cyproheptadine, which can cross the blood-brain barrier and have a greater impact on the sleep cycle. Second-generation antihistamines, represented by loratadine and cetirizine, have a relatively minor effect. Dry mouth: also common with benadryl and ketotifen. Glaucoma: common with first-generation antihistamines such as doxepin. Liver and kidney damage: less likely to occur and can be monitored regularly if used for long periods of time (more than 1 month). In summary, the side effects of anti-allergic drugs are relatively minor, the highest incidence of drowsiness, dry mouth, etc. are also common side effects, liver and kidney function damage is less likely to occur, but still need to be vigilant, regular monitoring.