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Swollen lips

Swollen lips, or lip oedema, is when one or both lips enlarge or distend beyond their normal size. This swelling is caused by a build-up of fluid, or inflammation inside the lip tissue. It can have many causes, including injury, illness, certain medicines or allergies.

Swollen lips can be a sign of anaphylaxis – a severe allergic reaction – which requires immediate medical attention. In less serious cases, swelling may appear and disappear quickly, for example after chapping or sunburn. Swelling that develops over time and lasts longer may be a sign of infection or a more serious inflammation or condition.

Symptoms of swollen lips

Swollen or “fat” lips can be debilitating and painful. In some cases, people may have difficulty:

  • Eating
  • Drinking
  • Talking
  • Opening their mouth

Other symptoms that may occur along with lip swelling include:

Causes of swollen lips

Swollen lips may have a range of different causes, from mild conditions to more serious disorders, including infections, allergy, inflammation, injuries or an underlying medical condition.

Allergic reactions

Swollen lips are a common symptom of an allergic reaction. Contact with any allergen, from pet dander to certain foods or the wrong lip care product, can cause the immune system to react and protect itself. Swelling is one of the effects.

Anaphylaxis is a severe and potentially life-threatening form of allergic reaction that can cause swollen lips. It requires immediate medical attention. Symptoms may include:

If you experience any of these symptoms get emergency medical attention immediately. The condition can develop quickly, triggering an increased heart rate, weakness, a drop in blood pressure, shock and, ultimately, unconsciousness and death.

Food allergies

Common triggers of swollen lips include allergies to foods including:

  • Nuts
  • Shellfish
  • Dairy products
  • Egg whites
  • Sesame seeds

Other reactions that can trigger swollen lips include:


Swollen lips are a common symptom of angioedema. This is a swelling that is in the deeper layers of the skin that usually affects the eyes and lips. Angioedema is a quite common condition affecting between 10 - 20% of people during their lifetime.

Like anaphylaxis, angioedema may be caused by an allergic reaction.

Food allergies are the chief cause of allergic angioedema, affecting between 5 - 8% of children and 1 - 2% of adults. Key food triggers include shellfish, nuts, eggs and milk.

Other triggers of angioedema include:

Hereditary angioedema is a genetic form of angioedema that can also cause swollen lips. It’s caused by a faulty gene and is rare, affecting between 1 in 10,000 and 1 in 50,000 people.

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