Desloratadine, sold under the brand name Aerius among others, is a tricyclic H₁ inverse agonist that is used to treat allergies. It is the major active metabolite of loratadine.

It was patented in 1984 and came into medical use in 2001. It was brought to the market in the US by Schering Corporation, later named Schering-Plough.

Desloratadine is used to treat allergic rhinitis, nasal congestion and chronic idiopathic urticaria (hives). It is the major metabolite of loratadine and the two drugs are similar in safety and effectiveness. Desloratadine is available in many dosage forms and under many brand names worldwide.

An emerging indication for desloratadine is in the treatment of acne, as an inexpensive adjuvant to isotretinoin and possibly as maintenance therapy or monotherapy.

The most common side effects are fatigue (1.2%), dry mouth (3%), and headache (0.6%).

Co-administration with erythromycin, ketoconazole, azithromycin, fluoxetine, or cimetidine resulted in elevated blood plasma concentrations of desloratadine and its metabolite 3-hydroxydesloratadine in studies. However, no clinically relevant changes were observed.

Desloratadine is a selective H₁-antihistamine which functions as an inverse agonist at the histamine H₁ receptor.

At very high doses, is also an antagonist at various subtypes of the muscarinic acetylcholine receptors. This effect is not relevant for the drug's action at therapeutic doses.