First-generation antihistamine drugs such as diphenhydramine cause drowsiness, while second- and third-generation antihistamines such as cetirizine and loratadine are less likely to.
Obat antihistamin generasi pertama seperti diphenhydramine menyebabkan kantuk, sedangkan antihistamin generasi kedua dan ketiga seperti cetirizine dan loratadine memberi efek lebih sedikit.