What is Loratadine Tablets?

Loratadine tablets are antiallergic agents. They are highly effective, long-acting, oral tricyclic antihistamines with rapid onset and potent action, selectively antagonizing peripheral H₁ receptors. Additionally, loratadine exhibits certain anti-inflammatory properties, thereby alleviating various inflammatory conditions. So, what exactly is loratadine? The following section provides a detailed explanation.

Loratadine tablets belong to the second-generation antihistamines and are commonly used to treat allergic symptoms. Compared with first-generation antihistamines, a key advantage of loratadine is its lack of sedative effects. It is indicated for allergic rhinitis, acute or chronic urticaria, allergic conjunctivitis, hay fever (pollinosis), and other allergic dermatoses. Loratadine effectively relieves symptoms associated with allergic rhinitis—including sneezing, rhinorrhea, nasal pruritus, nasal congestion, as well as ocular itching and burning sensation. Following oral administration, nasal and ocular symptoms and signs improve rapidly. It is also suitable for alleviating symptoms of chronic urticaria, pruritic dermatoses, and other allergic skin disorders. However, note that loratadine may cause adverse reactions such as fatigue, drowsiness, headache, impaired concentration, and dry mouth. It must be taken strictly under medical supervision, and patients should maintain a light diet, avoiding spicy or irritating foods.

Knowledge Expansion: Mechanisms of Action of Loratadine Tablets

1. Antiallergic Effect

When allergic symptoms occur, antihistamines like loratadine exert their antiallergic effect primarily by blocking histamine activity, thereby reducing manifestations such as erythema, wheals, and rhinorrhea. Clinically, loratadine is widely used in allergic rhinitis, chronic urticaria, pruritic dermatoses, and other allergic skin conditions. Moreover, loratadine helps the body eliminate unidentified allergens—including pollen, dust, and even cold air.

2. Antagonistic Activity

Both in vitro and in vivo studies demonstrate that loratadine selectively antagonizes peripheral H₁ receptors. It poorly crosses the blood–brain barrier and thus lacks central nervous system depressant effects. Furthermore, loratadine exhibits negligible activity at acetylcholine or adrenergic receptors. In murine experiments, neither loratadine nor its metabolites were found to penetrate the blood–brain barrier.

The above provides an overview of loratadine tablets—what they are and how they work. We hope this information proves helpful to you.