A 50-year-old woman with facial swelling after dental treatment visited our emergency department. We initially suspected that the swelling was caused by a drug-induced allergy; therefore, the patient was administered anti-allergy therapy. However, the patient did not respond to the therapy. On the basis of examination and a medical interview, we suspected that the swelling was caused by hereditary angioedema (HAE). The condition was eventually diagnosed as type I HAE on the basis of low levels

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... f complement component 4 (C4) and C1-esterase inhibitor (C1-inh) and their functional activities. The patient was treated with a regimen of antifibrinolytics and 17-α-alkylated androgens for both short-term and long-term prevention of recurrence. The patient's medical interview revealed sudden death of a family member. Herein, we report 2 cases of HAE. In addition, we provide several arguments about the necessity of an epidemiologic survey on HAE, free access to HAE information, and establishment of a C1-inh supply system in our country.