Updated on December 8, 2025.
Hereditary angioedema (HAE) is a genetic disorder that causes recurring episodes of angioedema, which is a type of painful and severe swelling. These episodes can cause swelling in the layers of tissue underneath the skin, the gastrointestinal (GI) tract, and the upper airways. The face, hands, arms, legs, tongue, and genitals are common areas for this swelling to occur. Swelling in the GI tract is also common, and can cause cramping, diarrhea, and vomiting.
Swelling in the respiratory tract can block the airways and make it difficult for a person to breathe. Though this only occurs in a small percentage of HAE attacks, it is a life-threatening complication that requires immediate medical attention. This is a possibility that everyone with the condition should be aware of and prepared to address.
Due to these risks, people with HAE are advised to wear a medical ID, such as a bracelet, tag, or necklace. This can be important if a person with HAE needs emergency medical treatment. HAE attacks can look similar to allergic reactions, but do not respond to treatments used for allergic reactions. It’s important to have an action plan in place in the event that a person experiences an attack.
There is no cure for HAE, but there are therapies that can help a person manage the condition.
What happens in the body when you have HAE?
To understand how HAE is treated, it helps to review what is happening in the body when a person has HAE. The swelling that occurs during an HAE attack occurs when fluid leaks from blood vessels into tissues and becomes trapped.
Most cases of HAE are caused by genetic mutations that affect the production or functioning of a protein called complement component C1-esterase inhibitor (C1-INH). This protein helps regulate inflammation. When levels of this protein are too low or this protein is not functioning normally, it leads to an overproduction of an inflammatory substance called bradykinin. Too much bradykinin causes fluid to leak from blood vessels and accumulate in tissues.
There is also a rare type of HAE (called type III hereditary angioedema). People with this type have normal levels of functioning C1-INH, but other genetic mutations that cause fluid to leak from blood vessels.
How is HAE treated?
Because symptoms, the severity of attacks, and the frequency of attacks vary from person to person, treatment needs will vary from person to person. A treatment plan for HAE may include both acute and preventive therapies.
Acute therapies
Also called on-demand therapies, acute therapies are medications taken during an HAE attack to reduce swelling and shorten the duration of the attack. Taking an acute therapy during an attack can prevent symptoms from progressing into more serious complications. All people with HAE will be prescribed an acute therapy.
Preventive therapies
Also called prophylactic therapy, preventive therapies are medications taken to prevent HAE attacks from occurring. People who experience frequent and/or severe HAE attacks may take these therapies on a continuous basis.
Preventive therapies may also be taken for short periods of time when a person knows they are going to be exposed to trigger. For example, HAE attacks can be triggered by physical stress/trauma during medical procedures (including dental work). A person with HAE will take a preventive therapy for a period of time around a procedure to prevent attacks.
Short-term prophylaxis may also be considered during stressful life events, such as starting a new job, moving, or another change or circumstance that will likely cause a person significant stress.
Choosing a medication
There are multiple acute and preventive therapies available, and the choice of which one to use will be a decision to make with a healthcare provider. Treatment needs can also change over a person’s lifetime, and regular appointments with a healthcare provider are important to keep up with treatment needs.
Avoiding triggers
On the topic of triggers, identifying and minimizing exposure to triggers is another important focus for preventing attacks. In addition to medical procedures and emotional stress, common HAE triggers include:
- Infections like the cold or flu
- Hormonal changes, such as those caused by onset of puberty, menstrual cycles, menopause, and hormonal birth control
- Medications, including ACE inhibitors (a type of blood pressure medication) and NSAIDs (non-steroidal anti-inflammatory drugs)
- Repetitive physical tasks, like writing or yardwork, can also trigger symptoms in some people
Some people with HAE report that certain foods aggravate symptoms, and it’s worth recording what you eat when working to identify triggers. HAE can also coexist alongside food sensitivities, intolerances, and allergies.
It’s important to remember that HAE attacks are unpredictable. Approximately 40 percent of HAE attacks have an identifiable trigger, while the remainder have no identifiable trigger.
