Hereditary Angioedema

Overview

Hereditary angioedema (HAE) is a rare inherited condition that causes sudden swelling deep under the skin or in the lining of the gut or airways. 'Hereditary' means it runs in families. 'Angioedema' means swelling under the skin. The swelling is not usually itchy and does not look like raised hives. It can affect the hands, feet, face, lips, eyelids, belly, or throat.

HAE is rare. It affects a small number of people worldwide, so many doctors may see only a few cases in their career.

HAE affects all sexes and ethnic groups. Symptoms often start in childhood or the teenage years. Because it runs in families, relatives may also be affected or carry the gene.

Symptoms

Common symptoms

• Sudden swelling of the hands, feet, face, lips, or eyelids
• Swelling that is not itchy and does not look like raised hives
• Belly pain, nausea, vomiting, or diarrhea during a gut attack
• Swelling that builds up over hours and lasts about 2 to 5 days
• A tingling or tight feeling in the skin before swelling starts
• Swelling after dental work, injury, stress, or infection

Symptoms in children

• Colic-like belly pain or vomiting that may be mistaken for other stomach problems
• Swelling of hands, feet, face, or lips
• Symptoms may start before puberty and change over time
• Throat swelling can happen at any age and needs emergency care

Symptoms in older adults

• Some people are diagnosed later in life after years of unexplained swelling
• The same swelling patterns can occur, but other health conditions and medicines should be reviewed
• Throat and belly attacks can still be serious, so an agreed action plan is important

Causes

Main causes

• HAE is usually caused by a change in a gene that affects a protein called C1 inhibitor. This protein helps control swelling in the body.
• The gene change is often passed from parent to child. A child has a 50% chance of inheriting it if one parent has the condition.
• Sometimes the gene change happens for the first time in a person, so there may be no family history.
• There are different types of HAE, and specialist tests can help find the exact type.

Risk factors

• Having a parent, sibling, or child with HAE
• Hormonal changes such as puberty, pregnancy, or some hormonal medicines
• Stress, infection, injury, dental work, or surgery can trigger attacks
• Some medicines can make swelling more likely; ask your doctor or pharmacist to review your medicines
• Many attacks happen without a clear trigger

When to see a doctor

See a doctor urgently if:

• You have swelling of the face, lips, or tongue for the first time
• You have severe belly pain with vomiting or diarrhea
• You have a known HAE attack that is not following your agreed plan
• You have swelling after dental work, injury, or surgery
• You are unsure whether your symptoms are an HAE attack

Book a routine appointment if:

• You have repeated unexplained swelling, even if it is mild
• A family member has HAE and you want to be checked
• You need a review of your treatment plan or medicines
• You are planning dental work, surgery, travel, or pregnancy and want advice

Diagnosis

A doctor will ask about your swelling episodes, family history, and triggers, and will examine you. They may refer you to a specialist in immunology or allergy. Blood tests can check the proteins involved in HAE. Genetic testing may be used in some cases.

Tests that may be done

• Blood tests for complement proteins, including C4 and C1 inhibitor level and function
• Genetic testing in some families
• Blood tests for relatives who may be affected
• Review of medicines and other possible causes of swelling

What to expect at your appointment

Test results may take a few weeks. Your specialist will explain what the results mean and help build a personal action plan. Finding HAE early, especially in children, can help prevent serious attacks.

Treatment

There is no cure for HAE, but it can be managed. Treatment aims to stop attacks quickly, prevent future attacks, and keep you safe during dental work, surgery, or travel. A specialist will tailor a plan to you.

Self-care at home

• Learn your early warning signs and follow your personal HAE action plan
• Carry medical information that says you have HAE
• Tell family, friends, and coworkers how to help in an emergency
• Avoid known triggers when you can, and ask your doctor to review medicines
• Keep regular dental and health checks, and plan ahead for procedures

Medical treatments

Treatment is decided by a specialist. Some medicines are used during an attack to stop swelling quickly. Other medicines are taken regularly to prevent attacks. Extra preventive treatment may be planned before dental work or surgery. Never start, stop, or change medicines without advice from your healthcare team.

When is surgery considered?

Surgery is not a cure for HAE. If you need surgery or dental work, tell the team well in advance that you have HAE, because preventive treatment may be needed around the procedure.

Living with this condition

Many people with HAE live full lives with a clear plan. Know your triggers, keep your emergency information with you, and make sure people close to you know what to do if swelling affects your breathing.

Lifestyle tips

• Get enough sleep and manage stress where possible
• Stay active in ways you enjoy and that feel safe for you
• Avoid known triggers and ask your doctor to review your medicines
• Plan ahead for travel, school, work, dental visits, and procedures
• Keep your HAE action plan up to date

Diet and exercise

There is no special diet that cures HAE. Eating a balanced diet and drinking enough fluids supports general health. Gentle or regular exercise is usually safe and helpful. If exercise triggers swelling for you, talk with your specialist about adjustments.

Mental health and emotional wellbeing

Living with a rare condition can cause worry, low mood, or anxiety, especially around attacks. These feelings are common and treatable. If you feel overwhelmed, anxious, or unsafe, contact your local crisis service or emergency services. You are not alone, and support is available.

Prevention

You cannot prevent inheriting the gene that causes HAE. But you can reduce the impact of the condition by avoiding known triggers, following a specialist plan, and using preventive treatment when recommended.

Vaccines

There is no vaccine for HAE. Keep up with routine vaccines recommended by your healthcare provider, and discuss any vaccine plan with your specialist.

Screening programmes

Family members can be offered blood tests and genetic counselling. Screening can find HAE before severe symptoms, especially in children. Ask your specialist how relatives can be checked.

Complications

If left untreated

• Swelling in the throat or airway can block breathing and become life-threatening
• Repeated belly attacks can lead to hospital stays and unnecessary tests or surgery
• Attacks can cause missed school, work, or family events
• Ongoing worry about when an attack will happen can affect mental health
• Rarely, severe attacks can cause serious dehydration or other problems

Long-term outlook

With early diagnosis, a personal action plan, and specialist care, most people with HAE can reduce attacks and live full lives. HAE is rare and can be serious, but it can be managed. Seek care early if you have breathing symptoms or a severe attack.

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