Loratadine

Loratadine, drug used to relieve symptoms of seasonal allergies and hives. Loratadine blocks the action of histamine, a chemical released in the body during allergic reactions, thereby inhibiting the development of symptoms such as sneezing, swelling mucous membranes, and itching eyes.

Available by prescription only, the typical dosage for adults and children over the age of 12 is 10 mg once a day. Loratadine should be taken on an empty stomach because food may delay its absorption. People with impaired liver or kidney function and the elderly may need smaller and less frequent doses. The drug is usually effective in one to three hours.

Loratadine may impair mental alertness, and activities requiring mechanical skills, such as driving, should not be performed until the effects of the drug have been determined. The safety and effectiveness of loratadine in children under the age of 12 are not understood, and its effects during pregnancy have not been thoroughly studied. This drug should not be used by breast-feeding mothers or people undergoing skin tests for allergies.

The most common side effects of loratadine are skin rash, headache, drowsiness, or dizziness. Less common side effects include heart rhythm disturbances and skin sensitivity to sunlight.

Extreme drowsiness may result if loratadine is used with other central nervous system depressants such as alcohol, barbiturates, tranquilizers, muscle relaxants, narcotics, pain medication, or tricyclic antidepressants. Monoamine oxidase (MAO) inhibitors, a class of antidepressants, can increase the side effects of loratadine.

Loratadine taken concurrently with the antifungal drugs ketoconazole, itraconazole, or fluconazole may cause serious heart rhythm disturbances. Antibiotics such as azithromycin, clarithromycin, or erythromycin may have a toxic interaction with loratadine.