What causes a swollen bottom lip?

A bitten lip, burn from hot food, cracked skin, or pressure can cause local swelling and tenderness. New lip balm, toothpaste, cosmetics, or food may trigger irritation or allergy. A painful bump, warmth, pus, fever, or a crusted sore can point to infection, while tooth or gum pain can refer swelling into the lip. Recurrent swelling without an obvious trigger may be angioedema, which affects deeper skin layers and can appear with hives or occur alone. The timing, pain, rash, and involvement of the tongue or throat help guide assessment.

Remove a suspected new lip product or food exposure, rinse gently, and use a cool compress wrapped in cloth. Avoid squeezing a lump or applying irritant home remedies. Drink fluids if comfortable and arrange dental review for tooth pain or gum swelling. Record what you ate, used, or took before the swelling and whether it has happened before. Do not take a new medicine for the reaction unless a clinician or pharmacist confirms it is suitable for you.

Call emergency services for swelling of the tongue or throat, trouble breathing or swallowing, wheezing, voice change, dizziness, or faintness. Seek same-day assessment for rapidly worsening swelling, widespread hives, severe pain, fever, pus, or facial swelling near an infected tooth. A clinician should review recurrent or unexplained episodes, even when they settle, because prevention depends on identifying the trigger.

Ask whether the swelling fits allergy, angioedema, infection, trauma, or a dental cause; what triggers to avoid; and what action plan to follow if the lips, tongue, or throat swell again.