Being a part of the medicine Allegra - fexofenadine it is an antihistamine with a selective antagonistic activity to H1-receptors without anticholinergic and blocking alfa1-adrenergic receptors; also at fexofenadine isn't observed a sedative action and other effects from the central nervous system. The antihistaminic effect of Allegra is observed in 1 hour, reaching its maximum in 6 hours, and proceeds within 24 hours. After 28 days of taking the medicine there wasn't observed the accustoming to it.