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Angioedema hereditarium
Swellings that look like an allergy but are not — which is why antihistamines and cortisone do not work here.
Also known as: HAE · C1 inhibitor deficiency · bradykinin angioedema · swelling attacks · SERPING1
Open in the tool — with search and all the links →This compilation is for information and replaces neither medical diagnosis nor treatment. If you have symptoms, see a doctor.
A rare inherited disease with recurring swelling attacks — and one of the most stubbornly misinterpreted of all. The decisive difference from allergy lies in the mechanism: it is not histamine at work here but bradykinin, a body’s own messenger that makes vessels leaky. The cause is a deficiency or malfunction of the C1 inhibitor, usually through a change in the SERPING1 gene. About 85 percent have too little of it, around 15 percent a normal amount that does not work properly. Inheritance is autosomal dominant, with about a fifth of cases arising anew — so nobody in the family need be affected. Precisely here lies the great practical consequence: because no histamine is involved, the usual emergency remedies for allergy — antihistamines, cortisone and adrenaline — do not work in this disease. Those who do not know this treat a supposed allergy for years without success. Attacks affect three areas: the skin, with swelling of face, hands, feet or genitals that usually does not itch and is not red; the abdomen, with severe cramps, nausea, vomiting and diarrhoea — complaints that have already led to unnecessary emergency operations; and, most dangerously, the larynx, where swelling can block the airway. Attacks are often triggered by injuries, dental treatment and operations, by psychological strain, infections, and by certain medicines. The laboratory diagnosis is simple and telling: a low C4 is the first clue, supplemented by the amount and function of the C1 inhibitor. Treatment runs on two tracks — agents that specifically stop an ongoing attack and, if needed, a preventive long-term treatment. Indispensable are an emergency card, an emergency medicine to carry, and a plan for dental visits and operations. After dental work or an operation the swelling usually comes with a delay — four to thirty-six hours afterwards, on average fourteen; a swelling at the larynx can appear up to twenty-four hours later.
Antihistamines, cortisone and adrenaline target histamine — with a bradykinin angioedema they come to nothing. Knowing this prevents dangerous delays in an emergency.
In an emergency the right thing must happen at once. A card names the diagnosis and the fitting agent, ideally carried along — with swelling in the throat every minute counts.
A lump in the throat, trouble swallowing, hoarseness or breathlessness mean immediate help — emergency call 144. Do not wait to see if it settles.
Procedures in the mouth and throat are a classic trigger. Informing early allows preventive treatment — that avoids attacks rather than treating them.
Severe abdominal cramps without fever that come and go belong to the picture. If the diagnosis is known, unnecessary emergency operations can be avoided.
Some blood pressure and hormone preparations can promote attacks. The list belongs reviewed — do not stop anything on your own.
The trait is passed on dominantly. A simple C4 is a good first step for relatives — knowing protects directly here.
In hereditary angioedema, antihistamines, cortisone and adrenaline do not work — that is the single most important sentence, because the swelling runs through bradykinin and not through histamine. What works is icatibant and C1 inhibitor concentrate, given within the first hours. For prevention there are drugs that clearly lower the number of attacks. An emergency card and a supply at home belong to it, because swelling of the larynx becomes life-threatening within hours.
About one in fifty thousand people is affected. An attack builds over two to six hours, lasts two to five days and then settles by itself. In about half it announces itself hours beforehand with a ring-shaped, non-itchy skin sign. Untreated, it occurs on average every one to two weeks to months. The C4 level is low between attacks — the simplest screening test. The time to diagnosis averages ten years.
That is the decisive difference from an allergy: the skin over the swelling is pale and does not itch, there are no raised red patches.
If the usual emergency treatment for an allergy does nothing and the swelling still goes down by itself over two to five days, that is a strong pointer to a different mechanism.
Violent belly pain with vomiting and diarrhoea, without fever — from a swelling of the bowel wall. Many people have had an unnecessary abdominal operation because of it.
Often a ring-shaped, non-itching skin patch or a tingling comes first. The attack is set off by pressure, injury, dental work, stress — and by certain blood pressure drugs and the pill.
A lump in the throat, a changed voice, trouble swallowing: that is the part that can become life threatening, and the reason people carry an emergency medicine and a card.
The most important first clue: in HAE, C4 is typically low — even between attacks. A simple, widely available test.
Assessed in acquired forms of C1 inhibitor deficiency — helps distinguish inherited from acquired.
Skin and lining renew themselves quickly and need zinc for it. With places that heal badly, cracked corners of the mouth and frequent skin infections a lack is a serious possibility.
Without vitamin C no stable collagen forms — the wound closes but holds less well. With a very one-sided diet, smoking and alcohol the intake is often tighter than assumed.
Steers the horn-forming of the skin. Too little makes it rough and dry, too much over longer periods harms liver and bone — and in pregnancy a strict upper limit applies.
Every healing needs building material. Anyone eating little during an illness loses exactly that — a sufficient amount spread across the day belongs to the treatment.
The most important sentence first: antihistamines and cortisone do not work on this form of swelling, although it looks like an allergic one. The reason is a different messenger — bradykinin instead of histamine. Not knowing that costs time in an attack.
If prevention is run through androgens, bone belongs watched alongside — together with liver values and blood fats. Vitamin D and calcium are the groundwork, not the treatment.
The most important point: oestrogen markedly worsens this condition — the combined pill can trigger attacks, and in pregnancy they often increase. Progestogen-only preparations are the more tolerable choice here.
The second decisive point: cortisone and antihistamines do not work on this swelling — unlike with the allergic kind. Anyone who does not know this treats a life-threatening throat attack with something that achieves nothing.
The swellings come from a protein deficiency in the complement system, not from histamine. Elimination diets change nothing — said plainly so no one loses time.
The swellings arise through the bradykinin system, not through histamine. Elimination diets and antihistamines therefore do not work — said clearly so no time is lost during an attack.
AWMF 061-029 · S1 · 2019-01 — expired
Hereditäres Angioödem durch C1-Inhibitor-Mangel
checked 2026-09 · last looked for a successor 2026-09-20