Angioedema can be caused by a number of triggers, both food or environmental, which results in the release of histamine by the body’s immune system. The mechanism of angioedema is similar to that of hives and these two conditions often present concurrently. While hives tend to affect the superficial layers of the skin, in angioedema the swelling and inflammation is seen in the deeper layers of the skin. Since angioedema may occur in soft tissues such as the mouth, eyelids, and genitals, it can rapidly become a life-threatening condition.