A plain-language guide

Hereditary Angioedema

What is known, what is still uncertain, and what is actively debated, written plainly, and built only from published medical research.

Early map · 33 sourced statements Every statement names its source Updated 2026-06-11
Please read this first. This guide is a companion to your medical team, not a replacement, and it is not medical advice. Everything here is tied to published research. If something you expected is not here, it almost always means we have not mapped a source for it yet, not that it is unknown to medicine. Hereditary Angioedema is an early, growing map, so it will look incomplete on purpose: we would rather show less and have every line be something you can check than fill the page with claims we cannot stand behind. For anything about your own situation, your clinicians hold the full picture. How this guide is built and why.

What it is

Hereditary angioedema is a genetic condition that causes repeated episodes of swelling deep under the skin and in the body's internal linings. The swelling is usually driven by a natural body chemical called bradykinin, and attacks that affect the throat (laryngeal edema) can be life-threatening.

Signs and symptoms

Decreased circulating C1-esterase inhibitor concentration

In the most common forms of HAE, the C1 inhibitor protein is missing or does not work properly. A blood test showing low C1 inhibitor function is a key way to confirm the diagnosis.

Limited evidenceSource: OMIM:106100
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:41560114
Notesplain_language confirmed from PMID:41560114 via curation 2026-06-11.
Last reviewed2026-06-11

Decreased circulating complement C4 concentration

Blood levels of a complement protein called C4 are usually low in HAE. A low C4 result is one of the standard tests used to help confirm the diagnosis.

Limited evidenceSource: OMIM:106100
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:41560114
Notesplain_language confirmed from PMID:41560114 via curation 2026-06-11.
Last reviewed2026-06-11

Laryngeal edema

Swelling can affect the throat and voice box (laryngeal edema). This is the most serious type of HAE attack because it carries a lifelong risk of becoming life-threatening, so it needs urgent treatment.

Limited evidenceSource: OMIM:106100
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:42165046
Notesplain_language confirmed from PMID:42165046 via curation 2026-06-11.
Last reviewed2026-06-11

Angioedema

Angioedema means episodes of swelling deep under the skin and in the linings of the body. In HAE these swelling episodes come and go and are the central feature of the condition.

Limited evidenceSource: OMIM:106100
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:40209692
Notesplain_language confirmed from PMID:40209692 via curation 2026-06-11.
Last reviewed2026-06-11

Autosomal dominant inheritance

HAE is usually passed down in an autosomal dominant pattern, which means a single altered copy of the gene is enough to cause it, and each child of an affected parent has about a 50% chance of inheriting it.

Limited evidenceSource: OMIM:106100
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:40209692
Notesplain_language confirmed from PMID:40209692 via curation 2026-06-11.
Last reviewed2026-06-11

Vomiting

Abdominal attacks can bring on nausea and vomiting alongside the belly pain.

Limited evidenceSource: OMIM:106100
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:40617599
Notesplain_language confirmed from PMID:40617599 via curation 2026-06-11.
Last reviewed2026-06-11

Abdominal pain

HAE attacks can involve the abdomen. Swelling in the gut wall may bring on recurring episodes of belly pain, which can be severe.

Limited evidenceSource: OMIM:106100
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:42165046, PMID:40617599
Notesplain_language confirmed from PMID:42165046 via curation 2026-06-11. plain_language confirmed from PMID:42165046 via curation 2026-06-11. plain_language confirmed from PMID:40617599 via curation 2026-06-11.
Last reviewed2026-06-11

Treatment and management

What the research describes, not a recommendation. Treatment decisions belong with your clinician.

This covers treatments that appear in the published research mapped here. Investigational and experimental therapies are not included, so their absence is a boundary of this map, not a sign they do not exist.

C1-inhibitor (C1-INH) concentrate

C1-inhibitor concentrate is a targeted treatment for hereditary angioedema. It replaces the missing C1-inhibitor protein, the underlying deficiency that drives attacks.

Used to help with: Angioedema, hereditary, 1.

Limited evidenceSource: PMID:33218838
The source text this rests on
“By contrast, several targeted, effective therapies are available, including C1-inhibitor (C1-INH) concentrates, which replace the missing protein activity underlying some bradykinin-mediated AE, and medications that directly lessen bradykinin activity (eg, ecallantide and icatibant).”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Notesconfirmed from PMID:33218838 via curation 2026-06-11
Last reviewed2026-06-11

Lanadelumab

Lanadelumab is a long-term preventive (prophylactic) treatment for hereditary angioedema. It is a monoclonal antibody that blocks plasma kallikrein, an enzyme that triggers attacks.

Used to help with: Angioedema, hereditary, 1.

Limited evidenceSource: PMID:40617599
The source text this rests on
“Acute treatment with Berinert was successful, and the patient was later placed on long-term prophylaxis with lanadelumab, which is a monoclonal antibody that inhibits Kallikrein.”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Notesconfirmed from PMID:40617599 via curation 2026-06-11
Last reviewed2026-06-11

Garadacimab

Garadacimab is a newer monoclonal antibody approved for long-term prevention of hereditary angioedema attacks. It blocks activated factor XII (FXIIa), an early trigger in the attack pathway.

Used to help with: Angioedema, hereditary, 1.

Limited evidenceSource: PMID:42057602
The source text this rests on
“The anti-FXIIa monoclonal antibody garadacimab is approved for long-term prophylaxis against HAE attacks.”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Notesconfirmed from PMID:42057602 via curation 2026-06-11
Last reviewed2026-06-11

Icatibant

Icatibant is an on-demand treatment used to stop an active hereditary angioedema attack. It works by directly lessening bradykinin activity, the mediator behind the swelling.

Used to help with: Angioedema, hereditary, 1.

Limited evidenceSource: PMID:33218838
The source text this rests on
“By contrast, several targeted, effective therapies are available, including C1-inhibitor (C1-INH) concentrates, which replace the missing protein activity underlying some bradykinin-mediated AE, and medications that directly lessen bradykinin activity (eg, ecallantide and icatibant).”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Notesconfirmed from PMID:33218838 via curation 2026-06-11
Last reviewed2026-06-11

Ecallantide

Ecallantide is an on-demand treatment used to stop an active hereditary angioedema attack. It is a plasma kallikrein inhibitor, blocking the enzyme that drives the swelling.

Used to help with: Angioedema, hereditary, 1.

Limited evidenceSource: PMID:40058753
The source text this rests on
“The peptide also exerted comparable anti-ischemic stroke effects to those of ecallantide (DX-88), a kallikrein inhibitor approved for the treatment of hereditary angioedema, in a mouse model of transient middle cerebral artery occlusion.”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Notesconfirmed from PMID:40058753 via curation 2026-06-11
Last reviewed2026-06-11

Sebetralstat

Sebetralstat (Ekterly) is the first pill taken on-demand to treat a hereditary angioedema attack. It is an oral plasma kallikrein inhibitor, recently approved for acute attacks in people aged 12 and older.

Used to help with: Angioedema, hereditary, 1.

Limited evidenceSource: PMID:41497064
The source text this rests on
“The recent FDA approval of Ekterly (sebetralstat), the first orally administered plasma kallikrein inhibitor for acute HAE attacks in patients aged 12 years and older, represents a landmark shift in the management of this rare disorder.”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Notesconfirmed from PMID:41497064 via curation 2026-06-11
Last reviewed2026-06-11

Berotralstat

Berotralstat is a once-daily pill taken to prevent hereditary angioedema attacks (long-term prophylaxis). It is an oral plasma kallikrein inhibitor.

Used to help with: Angioedema, hereditary, 1.

Limited evidenceSource: PMID:40716738
The source text this rests on
“Berotralstat is an oral, small-molecule plasma kallikrein inhibitor, approved as prophylaxis of HAE attacks in patients aged 12 years or older.”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Notesconfirmed from PMID:40716738 via curation 2026-06-11
Last reviewed2026-06-11

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How to read the evidence labels

Widely acceptedSpecialists broadly agree on this.
Strong evidenceBacked by solid, repeated research.
Moderate evidenceReasonable evidence, still being confirmed.
Limited evidenceSome evidence, but not yet convincing.
Early evidenceAn early finding that needs more study.
Experts disagreeResearchers actively disagree about this.

Where this comes from

This guide is built from 7 published source(s). Every claim above links back to one of them. Click any source ID to read the original on PubMed.

OMIM:106100 · Orphanet/HPO annotations for Angioedema, hereditary, 1
PMID:33218838 · Recognition and Differential Diagnosis of Hereditary Angioedema in the Emergency Department.
PMID:40058753 · Targeting the contact-kinin system: A cyclopeptide with anti-thromboinflammatory properties against stroke.
PMID:40617599 · Hereditary angioedema in a paediatric patient presenting with abdominal pain and duodenal dilation.
PMID:40716738 · Oral berotralstat for hereditary angioedema prophylaxis in patients aged 2 to <12 years: APeX-P interim results.
PMID:41497064 · Novel drug approval by the FDA: Ekterly (Sebetralstat), oral plasma kallikrein inhibitor for treating acute attacks of h
PMID:42057602 · Garadacimab for the long-term prophylaxis of hereditary angioedema.