Swollen Lip From an Allergic Reaction: What to Do

An allergy can cause fluid to move into deeper skin, producing sudden swelling of one or both lips. It may occur with itching, hives, facial swelling, flushing, nausea, wheezing, or throat tightness. The trigger may be a food, medicine, cosmetic, dental material, or insect sting, but the cause is not always obvious. Angioedema is the term used for deeper swelling of skin and tissues; read [Angioedema](/conditions/angioedema/) for more context. Lip swelling alone does not establish the cause, so timing and accompanying symptoms matter.

Stop using or eating anything that immediately preceded the reaction, unless it is a prescribed medicine that a clinician has told you not to stop. Keep the product packaging or a list of ingredients if available. Sit upright, stay with someone, and follow your personal emergency plan if you have one. Do not test the suspected trigger again. An antihistamine may help some mild allergic symptoms, but it does not replace emergency treatment when breathing or circulation is affected; use medicines only as directed by a healthcare professional or the label.

Call emergency services immediately for trouble breathing, wheezing, throat or tongue swelling, difficulty swallowing, voice change, dizziness, faintness, confusion, or rapidly spreading symptoms. Use prescribed adrenaline or epinephrine as instructed in your emergency plan. Even if symptoms improve, urgent assessment may be needed because serious reactions can return. Seek same-day medical advice for new unexplained swelling, repeated episodes, or swelling after a medicine.

Ask which trigger is most plausible, whether you need an allergy evaluation, which medicine is appropriate for mild symptoms, and whether you should carry an emergency treatment plan.