Aerius starts working within 30 minutes and will remain effective for 24 hours. It does not induce drowsiness, so you can take it any time of the day with or without any food or drink. Aerius is a unique triple,action formulation that is fast, powerful and long,acting and can provide a rapid and complete relief to symptoms of Allergic Rhinitis such as sneezing, nasal discharge, nasal itching, congestion, stuffiness, as well as ocular itching, tearing and redness, itching of the palate, and 91ing. Aerius is also effective in the treatment of the symptoms of Urticaria, as it effectively relieves itching and reduces the size and number of hives.