Recognizing HAE is often difficult due to the wide variability in disease expression. The course of the disease is diverse and unpredictable, even within a single patient over their lifetime. This disease may be similar in its presentation to other forms of angioedema resulting from allergies or other medical conditions, but it is significantly different in cause and treatment. When HAE is misdiagnosed as an allergy it is most commonly treated with steroids and epinephrine, drugs that are usually ineffective in treating a HAE episode. Other misdiagnoses have resulted in unnecessary exploratory surgery for patients with abdominal swelling and other HAE patients report that their abdominal pain was wrongly diagnosed as psychosomatic.