HAE Day Date in the current year: May 16, 2025

Hereditary angioedema (HAE) is a rare genetic disorder that affects approximately 1 in 10,000 to 1 in 50,000 people worldwide. It is characterized by recurrent, painful episodes of severe swelling of the skin or mucous membranes.

HAE is caused by one of several mutations that affect the production of a protein called C1 inhibitor, which helps control inflammation and keep blood vessels from leaking fluid. In people with HAE, either the body doesn’t make enough C1 inhibitor or the protein doesn’t work properly. This leads to the build-up of bradykinin, a peptide that promotes inflammation and causes fluid to leak from blood vessels, resulting in swelling.

Swelling episodes in people with HAE can affect the hands, feet, face, genitals, gastrointestinal tract, or larynx (airway). Swelling in the gastrointestinal and respiratory tracts is particularly dangerous. Episodes involving the gastrointestinal tract can cause abdominal cramping, vomiting, diarrhea and dehydration, while episodes involving the respiratory system make breathing difficult and carry a 25% risk of death by suffocation if left untreated. HAE can significantly reduce quality of life due to the unpredictable nature of attacks and the pain they cause. Episodes can affect a patient’s ability to perform daily activities and lead to the development of depression and anxiety.

HAE is very rare and relatively unknown, so many doctors aren’t familiar with its symptoms. In addition, swelling can be caused by many more common conditions. As a result, patients with HAE are often misdiagnosed and receive the wrong treatment. In many cases, it takes years for the disease to be correctly diagnosed.

Treatment of HAE includes prevention and acute treatment (management of attacks). There are three main types of medications used to treat HAE: C1 inhibitor replacement therapy, which replaces the missing or defective C1 inhibitor; kallikrein inhibitors, which block the kallikrein enzyme involved in the production of bradykinin; and bradykinin receptor antagonists, which block the effects of bradykinin.

HAE Day was established in 2002 by HAE International (HAEi), a global non-profit network of patient organizations from more than 100 countries around the world dedicated to improving the lives of people living with HAE. It is observed annually on May 16 to raise awareness of HAE among healthcare professionals and decision-makers, industry representatives and the general public, and to advocate for early diagnosis, improved care and accessible treatment.

You can get involved with HAE Day by learning more about hereditary angioedema and sharing what you’ve learned with others, attending an event organized by your national HAE organization, participating in the annual HAE Day Activity Challenge, donating to an organization that supports HAE patients or funds research, and spreading the word on social media using the hashtag #HAEDay.