过敏时，体内释放的组胺会导致打喷嚏和皮肤发痒。

During an allergy, ___histamines released in the body cause sneezing and itchy skin.

抗组胺药通过阻断组胺的作用来缓解过敏症状。

Antihistamines work by blocking the effects of ___histamines that cause allergy symptoms.