Allergic Reaction: This is often the most common cause of facial swelling, typically resulting from an allergic response to substances like insect bites, certain foods, or medications. The swelling is usually accompanied by other symptoms such as redness, itching, and possibly difficulty breathing.

Dental Infection: Infections of the teeth or gums can cause swelling of the face, particularly if the infection spreads to surrounding tissues. Symptoms may include toothache, fever, and localized pain.
Sinusitis: Inflammation or infection of the sinuses can lead to facial swelling, especially in the areas around the eyes and nose. Other symptoms include nasal congestion, headache, and facial pain.
Cellulitis: A bacterial skin infection that can cause redness, swelling, and warmth of the skin. It often starts as a small area of redness that spreads, and can be accompanied by fever and chills.

Angioedema: A severe, potentially life-threatening allergic reaction that can cause rapid swelling of the face, lips, tongue, and throat. It can lead to airway obstruction if not promptly treated.
Ludwig's Angina: A severe infection of the tissues in the neck, which can cause swelling of the face and neck, and potentially lead to airway obstruction. It requires immediate medical attention.
Cavernous Sinus Thrombosis: A rare but potentially deadly condition where a blood clot forms in the cavernous sinus, leading to facial swelling, headache, and possibly blindness or stroke.

Sarcoidosis: A condition where inflammatory cells form lumps known as granulomas in various parts of the body, including the face, leading to swelling.
Melkersson-Rosenthal Syndrome: A rare neurological disorder characterized by recurrent, often unilateral, facial paralysis or weakness, swelling of the face and lips, and the development of folds and furrows in the tongue.
Superior Vena Cava Syndrome: Obstruction of the superior vena cava can cause facial swelling, particularly in the upper part of the face, along with shortness of breath and arm swelling.