Reversible inhibitors of H₁ histamine receptors.

First generation: Diphenhydramine, dimenhydrinate, chlorpheniramine ("-en/-ine" or "-en/-ate")- Clinical use: Allergy, motion sickness, sleep aid- Adverse effects: Sedation, antimuscarinic, anti-α-adrenergic

Second generation: Loratadine, fexofenadine, desloratadine, cetirizine ("-adine)- Clinical use: Allergy- Adverse effects: Less sedating than 1st generation because of ↓ entry into CNS