Extrinsic asthma occurs in atopic individuals who often have a strong family history for allergivc manifestations,including asthma,hay fever,and urticarial eruptions.

• 外源性哮喘常常发生于有明显家庭过敏史，包括哮喘、枯草热及荨麻疹等的遗传性、过敏性个体。