Hereditary angioedema: attack treatment & prophylaxis

For confirmed or strongly-suspected HAE (C1-INH deficiency, type I/II, or HAE with normal C1-INH): routes an acute attack to early on-demand therapy, and names the agents that do NOT work and why, separates short-term (procedural) prophylaxis, and walks first- versus second-line long-term prophylaxis. Bakes in the bradykinin-vs-histamine teaching, the fresh-frozen-plasma caveat, and the pregnancy/lactation/child rules.

Evidence tier: Guideline-derived.

Decision points

What do you need to manage now?
Airway (laryngeal / tongue / throat) involvement?
Start long-term prophylaxis?

Do-not-miss pitfalls

Antihistamines, corticosteroids, and epinephrine do NOT reverse HAE attacks, their failure is a diagnostic clue, not a reason to redose, and must never delay targeted on-demand therapy.
Laryngeal, tongue, or throat swelling carries substantial mortality, treat immediately and seek emergency care even after self-treatment, with a low threshold for early elective intubation.
Fresh frozen plasma can precipitously WORSEN an attack: it supplies bradykinin-generating substrate (HMW kininogen, prekallikrein, factor XII) as well as C1-INH. Use only when no approved on-demand agent is available, prefer solvent-detergent–treated plasma, and protect the airway.
Every patient, even on long-term prophylaxis, must keep ≥2 doses of on-demand medication and a written action plan; prophylaxis reduces but does not eliminate attacks.
Do not require patients to fail anabolic androgens before offering first-line long-term prophylaxis; androgens are second-line with a heavy side-effect burden.
In pregnancy, lactation, and children, plasma-derived C1-INH is the preferred agent across on-demand, short-term, and long-term prophylaxis; anabolic androgens are contraindicated in pregnancy/lactation and avoided in children, and tranexamic acid is excreted in breast milk.
Estrogen-containing contraceptives or HRT and ACE inhibitors can trigger or worsen HAE, avoid them.
Ecallantide must be administered by a healthcare professional (anaphylaxis risk, black-box warning); the other on-demand agents are self-administered.

Evidence & citations

Clinician decision support. Verify against the cited source. Not a substitute for clinical judgment. 100% on-device; no patient data is stored or transmitted.