What causes angioedema?

Chemical signals can make tiny blood vessels more permeable, allowing fluid to move into deeper layers of skin. Swelling may affect the lips, eyelids, face, hands, feet, or genitals. Hives often occur alongside the swelling when histamine is involved, but angioedema can also occur without a raised itchy rash.

Triggers include foods, insect stings, latex, infections, and some medicines. A family form can result from an inherited problem with the proteins that regulate swelling. In other cases, no single trigger is found. The cause matters because treatment differs between histamine-driven and non-histamine forms.

Record what happened before the swelling, including new foods, medicines, stings, illness, or exercise, and take photographs if safe. Do not stop a prescribed medicine without medical guidance, but contact the prescriber promptly if swelling began after a new drug. A clinician may review the timing, examine the skin, and arrange testing when episodes recur or a family pattern is present.

Call emergency services immediately for swelling of the tongue, mouth, or throat, trouble breathing, wheezing, difficulty swallowing, a hoarse voice, faintness, confusion, or rapidly worsening symptoms. These signs can obstruct the airway or signal a severe allergic reaction. Do not wait to see whether facial swelling settles. For swelling without breathing or swallowing symptoms, arrange prompt medical advice, especially when the cause is new or unclear.

Ask whether the episode fits histamine-related angioedema, a medicine reaction, or another form; which triggers to avoid; and what emergency plan to follow. If attacks recur, ask whether family history or specialist testing should be considered.