Hereditary angioedema: symptoms, attacks and treatment in the UK

Angioedema is sudden swelling of tissues beneath the skin or lining of the gut and airway. The NHS describes five types: acute allergic, non-allergic reactions to medicines (most commonly ACE inhibitors), idiopathic (cause unknown), hereditary, and acquired. It calls hereditary angioedema a rare and potentially life-threatening type that is often inherited from your parents.

In the common allergic types, swelling is usually accompanied by hives and responds to antihistamines. HAE is different. HAE UK emphasises that HAE-related swelling is not the same as swelling caused by allergies, which is why standard allergy treatments do not help and why recognising it matters.

According to HAE UK, HAE is characterised by large swellings of the tissues lasting from three to five days. They may occur on the hands and feet, arms and legs, trunk, intestines, genital organs, face, tongue, neck and airway. Intestinal swelling causes sickness, diarrhoea and very severe pain, and swelling of the face and tongue can progress to the airway.

Some people notice warning symptoms in the 24 hours before an attack, which HAE UK says can include extreme tiredness, a rash or tingling over the affected site. Attacks can begin from early childhood, adolescence or later in life, and frequency varies from once or twice a year to every few days in the most severely affected people.

• Swelling of the hands, feet, face, genitals or neck that lasts for days.

• Severe abdominal pain with sickness or diarrhoea, which can occur without any visible swelling.

• Swelling of the tongue, throat or voice box, which can threaten breathing.

• A tingling feeling, tiredness or rash before an attack.

The NHS says to call 999 if your lips, mouth, throat or tongue suddenly become swollen, if you are breathing very fast or struggling to breathe, if your throat feels tight or you are struggling to swallow, or if you suddenly become very confused, drowsy or dizzy. It says throat swelling leading to breathing difficulties is a medical emergency needing immediate treatment, and to ask for an urgent GP appointment or NHS 111 help if part of the body suddenly becomes swollen.

Because HAE does not respond to antihistamines, steroids or adrenaline according to HAE UK, people with a diagnosed HAE should follow the emergency plan agreed with their specialist team and make sure that emergency staff know the diagnosis.

HAE UK states that a parent with HAE has a 50% chance of passing it on to each child, and that family members who have been tested and do not have HAE will not pass the disease on to their children. It can also arise as a spontaneous gene mutation in someone with no family history, so a negative family history does not exclude it.

Because of this, people with a confirmed diagnosis are usually encouraged to have close relatives tested. Genetic counselling, when offered, can help families understand what the results mean.

HAE is rare, and HAE UK says patients often remain undiagnosed for many years. If a person has repeated unexplained swelling, abdominal pain episodes or a family history, a GP can refer to an immunology or allergy specialist who can arrange the specific blood tests.

For angioedema in general the NHS lists identifying and avoiding the underlying cause, antihistamines and steroid tablets, and says that people with hereditary angioedema may also need medicine to stop attacks happening and regular reviews to check whether treatment is working. Specific HAE medicines are prescribed by specialist centres, and this guide does not describe individual products because the sources read did not detail them.

Living with a condition that comes in unpredictable episodes can be unsettling. Practical steps include keeping a record of attacks, understanding which early symptoms signal an attack, and carrying a letter or card explaining the diagnosis. If the swelling affects the airway, tell emergency staff the diagnosis as soon as you arrive. Ask your team about support organisations such as HAE UK.

HAE is usually managed in NHS specialist immunology services because of the rarity of the condition and the need for emergency treatment plans. Private immunology consultations are sometimes used for a second opinion, but ongoing prescribing and emergency planning are generally coordinated with the NHS specialist centre.