Clarinase Repetabs is indicated for seasonal allergy symptoms when accompanied by nasal congestion. It contains a combination of loratadine (an antihistamine) and pseudoephedrine (a decongestant). Antihistamines help reduce allergic symptoms by preventing the effects of a substance called histamine. Histamine is produced by the body in response to foreign substances which the body is allergic to. Decongestants produce narrowing blood vessels. This leads to clearing of the stuffy or blocked nose. Clarinase relieves symptoms associated with allergic rhinitis (hay fever), such as nasal and sinus congestion, sneezing, runny nose, watery, itchy eye. Clarinase Repetabs help to alleviate your allergy or common cold symptoms by stopping the effects of histamine, which is produced by the body when you are allergic to something. Clarinase provides 12-hour relief from seasonal allergy symptoms when accompanied by nasal congestion. It may not cause drowsiness.