Allergic Reaction, Swollen Lips

With food and drug allergy rates increasing, it is important to recognize common signs of an allergic reaction. Lip swelling is one manifestation of an allergic reaction, which may be accompanied by swelling of the mouth, tongue and/or throat. Known as allergic angioedema, this reaction occurs due to histamine release in response to an allergic trigger. This leads to fluid leakage into the deep skin layers, which causes swelling. Although angioedema of the lips, face, mouth and throat can occur from nonallergic causes, when the swelling is part of an allergic reaction, it can quickly progress to a life-threatening situation.

Close-up of a woman's lips. (Image: Tetra Images/Tetra images/Getty Images)


Allergy-related lip swelling -- with or without swelling of other parts of the face or mouth structures -- typically begins within a few minutes to an hour after exposure to an allergic trigger. The swelling is generally firm and the involved skin is not itchy, but there may be tingling or pain. The swelling is often not uniform, meaning one side is often more affected than the other. In addition to the lips and mouth, the area around the eye is commonly affected with this type of allergic reaction. Hives on other parts of the body often accompany allergic angioedema and are characteristically itchy. Breathing difficulty occurs when swelling involves the throat and/or tongue, a dangerous reaction that can lead to complete blockage of the airway if not treated immediately.

Common Causes

Many substances can cause allergy-related angioedema with lip swelling, but some culprits are more common than others. -- Medications: Allergic angioedema can occur with many medications. However, antibiotics, especially penicillin, are among the most common triggers. Sulfonamide and cephalosporin antibiotics, aspirin and contrast media used for certain types of x-rays are less common triggers. -- Foods: Cow's milk, eggs, peanuts, tree nuts, fish and shellfish are the most common foods that trigger allergic reactions, including angioedema. Additionally, some people with pollen allergies experience short-term burning and itchiness of the lips, mouth and throat, sometimes accompanied by mild swelling. This condition, known as oral allergy syndrome, occurs after eating certain types of raw fruit or vegetables, such as melons, apples, pears, celery, zucchini and cucumber. It occurs because some raw food proteins chemically resemble plant pollens and trigger an allergic reaction on contact with the lips and mouth.
-- Bites and stings: The bites of common household pests, such as spiders and ants, and the stings of wasps, yellow jackets and bees can cause an allergic reaction, including allergic angioedema.


Treatment for allergic angioedemia involving the lips depends on the severity of the reaction. For mild reactions or limited reactions that are not causing breathing difficulties, antihistamines are a first-line treatment because they block the action of histamine. Examples include diphenhydramine (Benadryl) and hydroxyzine (Vistaril).

In people with more severe reactions, corticosteroids -- such as hydrocortisone and prednisone -- are used to control the reaction by reducing the immune system response to the allergic trigger. Epinephrine is also used for severe allergic reactions. The medication counteracts the leakage of fluid into the tissues by causing blood vessel constriction. It has other benefits for people experiencing breathing difficulty or low blood pressure due to a severe allergic reaction.

Prevention, Warnings and Precautions

The best way to prevent allergic reactions like swelling of the lips and face is to completely avoid triggering substances. Allergy testing is often recommended to determine what substances a person is allergic to. For people who have had or are at risk for a severe, life-threatening allergic reaction, carrying of an epinephrine autoinjector (Adrenaclick, Auvi-Q, EpiPen) is typically encouraged.

Lip swelling from an allergy can be a sign of a serious and potentially life-threatening reaction. Call 911 or seek emergency medical care if you experience any of these symptoms along with lip swelling:
-- Wheezing, throat tightness or difficult breathing. -- Severe itching, hives or flushing of the skin. -- Dizziness, fainting or loss of consciousness. -- Trouble swallowing or a swollen tongue. -- Abdominal pain, nausea or vomiting.

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