HAE is unpredictable in nature with substantial variation in the frequency and the age of onset of attacks. Attack patterns vary with age and may affect a single site or multiple sites6. Most attacks of HAE last 2 to 5 days, resulting in 20 to 100 days of incapacitation per year. Acute episodes of HAE often occur without warning and often may be precipitated by a trigger. Common attack triggers include, but are not limited to1:
- Trauma
- Surgery
- Anesthesia
- Dental procedures
- Emotional stress
- Menstruation
- Oral contraceptive use
- Infections
There is little correlation between the symptoms of attack and the type of genetic defect present, even within the same family5. Furthermore, age and past attack patterns do not predict the site, severity, or speed of future attacks.