People in whom episodes occur at least once a month or who are at high risk of developing laryngeal edema require long-term prevention. There are several phase III clinical trials addressing HAE prophylaxis and therapy. These have led to the licensing of pdC1INH in many parts of the world; bradykinin receptor antagonists (icatibant) in Europe; kallikrein inhibitors (ecallantide and lanadelumab) in the United States; and recombinant C1-INH replacement therapy (rhC1INH; conestat alfa) in Europe. Tranexamic acid has been shown to be relatively ineffective therapy. Danazol prophylaxis remains an option but therapeutic agents are now being used more for prophylaxis because of danazol's adverse events. For people requiring long-term prophylaxis, home therapy which allows people to self-administer the product, is considered an integral part of allowing patients a normal quality of life.