When working with Hereditary Angioedema, a rare genetic disorder that triggers sudden swelling of the skin, lips, gut and airway. Also known as HAE, it can become life‑threatening when swelling blocks breathing.
The root cause lies in a mutation of the SERPING1 gene, which codes for C1 esterase inhibitor, the protein that controls the complement and contact systems in blood. When this inhibitor is missing or faulty, the body overproduces bradykinin, a peptide that relaxes blood vessels and makes tissues leak fluid. The excess bradykinin is the direct trigger for the rapid, painful swelling seen in HAE attacks. Understanding this chain—gene → C1 inhibitor → bradykinin—helps explain why certain drugs work while others do not.
Typical signs include facial or lip swelling, abdominal pain that mimics a bowel obstruction, and, most urgently, throat swelling that can cause stridor. Attacks often start without warning, but common triggers are stress, hormonal changes, trauma, or certain medications like ACE inhibitors. Because the swelling can progress in minutes, having an on‑demand rescue plan is essential. If the throat feels tight or you notice a rapid rise in swelling, call emergency services immediately—time is the difference between a quick treatment and a severe airway emergency.
Diagnosis rests on two lab tests: a functional assay of C1 esterase inhibitor activity and a measurement of complement component C4. Low C4 with reduced C1 inhibitor activity confirms HAE. Genetic testing can identify the specific SERPING1 mutation and is useful for family screening. Early diagnosis lets patients start prophylactic therapy before the first severe attack.
Treatment splits into two categories. On‑demand options abort an attack once it starts. The most common are icatibant, a bradykinin‑B2 receptor antagonist that blocks the swelling signal and plasma‑derived or recombinant C1 esterase inhibitor, which restores the missing protein and rapidly reduces swelling. Both are given by injection and have proven to cut attack duration in half.
Long‑term prophylaxis aims to keep attacks from happening at all. Options include androgens like danazol, monoclonal antibodies such as lanadelumab, a subcutaneous antibody that blocks plasma kallikrein and thus prevents bradykinin buildup, and regular infusions of C1 inhibitor. The choice depends on attack frequency, lifestyle, insurance coverage, and tolerance of side effects. Our collection of drug‑comparison guides makes it easier to weigh factors like efficacy, safety, dosing frequency, and cost across these options.
Beyond medication, lifestyle adjustments can lower trigger exposure. Keeping a symptom diary helps spot patterns—maybe a particular sport, a stressor, or a hormonal cycle. Over‑the‑counter NSAIDs should be avoided because they can worsen swelling in some patients. Staying well‑hydrated and managing stress through techniques like breathing exercises or yoga often reduces the number of mild attacks.
Family members of someone with HAE should consider genetic testing even if they have no symptoms yet. Early identification allows pre‑emptive education and the option to start prophylaxis before a first serious episode. Support groups and patient advocacy organizations also provide valuable resources, from coping strategies to updates on new therapies in clinical trials.
All the articles below dive deeper into specific medications, compare their pros and cons, and explain how to choose the right regimen for your situation. Whether you’re looking for a quick rundown of on‑demand rescue drugs or a detailed analysis of long‑term prophylactic options, the guides in this section give you the facts you need to make an informed decision.
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