Inhalation of allergens in sensitized subjects develops into bronchoconstriction within 10 minutes, reaches a maximum within 30 minutes, and usually resolves itself within one to three hours. In some subjects, the constriction does not return to normal, and recurs after three to four hours, which may last up to a day or more. The first is named the early asthmatic response, and the latter the late asthmatic response.