Sudden swelling on one side of the face

The location, speed of onset, pain, skin changes and symptoms in the mouth, eye or airway help narrow the cause. Swelling that is spreading quickly or affecting breathing or swallowing is an emergency.

Toothache, gum tenderness, a bad taste or pain when biting can accompany a dental abscess. Cellulitis often presents with skin that becomes warm, red, tender and progressively swollen. A salivary-gland blockage may cause pain near the cheek or under the jaw that becomes noticeable around meals.

Angioedema can present with rapid swelling of the lips, eyelids or face, sometimes after a food, medicine or insect sting. Sinusitis can produce cheek pressure with nasal blockage and discharge. Swelling confined near the eye needs particular care because vision and eye movement may be affected.

Arrange same-day clinical or dental advice for new painful facial swelling, especially with tooth symptoms, fever, redness or worsening size. Note when it began and any new foods, medicines, dental work, injuries or insect stings.

Do not squeeze the swollen area or place aspirin against a tooth or gum. Use only pain relief that is suitable for you, keep drinking if swallowing is comfortable, and remove contact lenses if the eyelid area is involved.

Call emergency services for difficulty breathing, throat tightness, tongue swelling, faintness, confusion, blue or grey lips, or a rapidly spreading raised rash. These can occur when anaphylaxis or severe angioedema affects the airway.

Seek urgent hospital assessment for swelling around the eye with reduced vision, double vision, pain on eye movement or inability to open the eye. Rapidly spreading redness, severe headache, marked drowsiness, trouble swallowing or difficulty opening the mouth also require urgent care.

Ask whether the likely source is dental, skin, sinus, salivary or allergic; whether imaging or dental treatment is needed; what medicine is appropriate; and which changes mean you should go directly to an emergency department.