An allergy can cause swollen lips. Swelling of the lips, tongue, face or throat are common symptoms of a food allergy, according to Mayo Clinic.
Allergies are the overreaction of the body's immune system to foreign substances, such as dust, pollen, or bee venom, that are usually harmless to most people. The severity of how the body reacts to allergies varies by individual. The reaction can range from minor irritation of the skin, sinuses, airways or digestive system to anaphylaxis, which is a potentially life-threatening medical situation where a person may go into shock. Common types of allergies include allergies to food, medicine, insect venom, animals, latex, and cosmetics, says WebMD.