Facial swelling, or edema, is the puffiness or enlargement of the face caused by fluid accumulation or inflammation in the tissues beneath the skin. Swelling localized only to the left cheek points toward a problem specific to that area, unlike bilateral swelling which suggests a systemic issue. This unilateral swelling is a common symptom that can arise from a range of sources, most often involving infection or irritation. Understanding the origin—whether from the teeth, glands, or soft tissues—helps determine the appropriate next step.
Dental and Jaw-Related Causes
Infections originating in the mouth are the most frequent cause of sudden, localized cheek swelling. A dental abscess is a pocket of pus created by a bacterial infection, commonly developing at the root tip of a tooth (periapical) or in the gums (periodontal). This infection can quickly spread to the surrounding facial tissues. The resulting swelling is usually firm, warm to the touch, and often accompanied by a severe, throbbing toothache that may extend to the jaw, neck, or ear on the same side.
The eruption of wisdom teeth, particularly the lower molars, can also lead to significant cheek swelling. If a wisdom tooth is impacted or partially erupted, the surrounding gum tissue can become infected, a condition known as pericoronitis. This infection causes inflammation and pain, resulting in noticeable swelling of the overlying cheek and sometimes making it difficult to fully open the mouth.
Severe gum disease, or periodontitis, can also contribute to facial swelling in advanced stages. This condition involves deep bacterial pockets forming around the teeth, which may lead to a localized gum abscess that pushes outward into the cheek tissue. Additionally, recent dental procedures, such as a tooth extraction, may cause temporary, localized swelling due to the body’s natural inflammatory response. Swelling that worsens after a few days, however, may indicate a developing infection.
Salivary Gland and Lymph Node Issues
The major salivary glands, particularly the parotid gland located near the cheek and ear, can be a source of unilateral swelling. Sialadenitis is a bacterial infection of the salivary gland that often presents as a painful lump in the cheek or under the jaw, sometimes accompanied by fever. This infection can also cause foul-tasting pus to drain into the mouth.
A blockage in the salivary duct, known as sialolithiasis or salivary stones, is a common precursor to sialadenitis. These small calcium deposits obstruct the flow of saliva, causing it to back up and the gland to swell painfully. Swelling caused by a salivary stone typically increases in size when a person eats or anticipates eating, as this triggers saliva production.
Swollen lymph nodes, a condition called lymphadenitis, can also manifest as cheek or jaw swelling. Lymph nodes are small, bean-shaped structures that swell as they filter out pathogens in response to a nearby infection. A tender, palpable lump under the jaw or in the neck on the left side may indicate the body is fighting an infection, such as a localized dental issue or a throat infection.
Diffuse Infections, Injuries, and Acute Reactions
Beyond the teeth and glands, swelling can arise from acute infections of the soft tissue itself. Cellulitis is a serious bacterial infection of the skin and underlying tissues that causes diffuse, rapidly spreading swelling. Unlike a localized abscess, cellulitis results in a generalized area of redness, warmth, and pain that lacks a clear boundary and can escalate quickly.
Physical trauma to the face, such as a fall or a blow, will immediately cause localized inflammation and swelling as blood and fluid accumulate. Swelling from an injury may also be accompanied by bruising or a visible break in the skin. Insect bites or stings can also lead to localized swelling, often with surrounding redness or itching, as the body reacts to the injected venom or irritant.
Acute allergic reactions can cause rapid facial swelling, a condition known as angioedema. This reaction is the body’s response to an allergen, such as a food or medication, involving the release of chemicals that cause fluid to leak into the deeper layers of the skin. This results in noticeable puffiness around the eyes, lips, and cheeks. While usually benign, angioedema can quickly become a medical issue if the swelling affects the throat and compromises the airway.
Recognizing Emergency Symptoms and Next Steps
While many causes of cheek swelling are treatable and resolve without complication, certain symptoms indicate a spreading infection or an airway risk requiring immediate medical attention. Any sudden and severe swelling accompanied by difficulty breathing, shortness of breath, or trouble swallowing should prompt an immediate visit to an emergency department. The inability to open the mouth fully (trismus) or a high fever with chills also suggests a severe, spreading infection that needs urgent intervention.
For non-emergency swelling, the first step is determining the likely source to seek the appropriate practitioner. If the swelling is associated with a painful tooth or recent dental work, a dentist should be consulted promptly, as dental infections require professional treatment. If no dental cause is apparent and the swelling is accompanied by systemic symptoms like fever and malaise, a general practitioner can help diagnose infections like sialadenitis or cellulitis. They often use imaging like X-rays or CT scans to pinpoint the source of the inflammation. Ignoring unilateral swelling is discouraged, as even a minor infection can spread to the deep spaces of the head and neck, potentially leading to life-threatening complications.