Swelling that appears suddenly on only one side of the jaw is a common symptom that often causes concern. This area houses a complex network of structures, including teeth, salivary glands, lymph nodes, and jaw joints. Unilateral swelling represents a localized reaction that can originate from many different biological processes. Determining the source is necessary for effective treatment, as the underlying cause could range from a simple infection to a more serious medical condition.
Swelling Caused by Dental and Gum Issues
Infections originating in the mouth are among the most frequent causes of localized jaw swelling. A periapical abscess is a pocket of pus that forms at the tip of a tooth root, typically due to untreated decay that allows bacteria to invade the tooth’s pulp tissue. As the infection progresses, inflammation and pressure push outward into the surrounding bone and soft facial tissues, causing visible swelling on the cheek or jawline. This can lead to throbbing pain that sometimes radiates toward the ear or neck.
A periodontal abscess forms within the gum tissue along the side of a tooth root, often as a complication of advanced gum disease. This occurs when bacteria become trapped in a deep pocket between the gum and the tooth, leading to localized infection and inflammation. The resulting swollen bump on the gum can cause the nearby jaw area to appear visibly enlarged. While the swelling may fluctuate as pressure builds or drains, the underlying infection requires professional treatment.
Pericoronitis is another common cause, involving inflammation of the gum flap covering a partially erupted tooth, most frequently a wisdom tooth. Food particles and bacteria easily become trapped beneath this flap, leading to a localized infection. This infection often causes tenderness, pain when biting down, and swelling localized to the back of the jaw. In severe cases, the infection can spread beyond the immediate gum line, causing the cheek and the nearby submandibular area to swell.
Swelling Caused by Glands and Lymph Nodes
The glandular and lymphatic systems in the neck and jaw region can cause unilateral swelling distinct from dental issues. Sialadenitis is a bacterial infection of a salivary gland, most commonly the parotid gland near the ear or the submandibular gland under the chin. This infection causes the affected gland to become firm, tender, and visibly swollen on one side of the face or jaw. Swelling is often accompanied by fever, chills, and sometimes a foul taste if pus drains into the mouth.
Sialolithiasis, or salivary stones, is a common trigger for sialadenitis. This condition involves a stone (sialolith) forming and obstructing the duct that carries saliva from the gland into the mouth. When the duct is blocked, saliva flow is impeded, allowing bacteria to multiply behind the obstruction. Patients often notice that the swelling intensifies during or just after eating, as the gland attempts to produce saliva that cannot be released.
Lymphadenopathy refers to the enlargement of lymph nodes, which are small, bean-shaped structures that filter harmful substances and produce infection-fighting cells. When a localized infection occurs, the lymph nodes draining that region swell as part of the immune response. Unilateral jaw swelling may indicate swollen submandibular or cervical lymph nodes reacting to a nearby infection, such as an ear infection, sore throat, or a skin infection on the face. Swollen lymph nodes typically feel like tender, movable lumps beneath the jawline or in the neck.
Swelling Caused by Jaw Structure and Muscle Use
Causes related to the jaw’s mechanics, joint, and musculature can also result in swelling, though often less dramatic than an acute infection. The temporomandibular joint (TMJ) connects the jawbone to the skull, and disorders of this joint (TMD) can cause localized inflammation. While pain and stiffness are typical symptoms, significant inflammation within the joint capsule can occasionally lead to mild facial swelling directly in front of the ear. This swelling is usually a result of an inflammatory process, such as arthritis affecting the joint, or from trauma.
Muscle use patterns can contribute to a swollen appearance, particularly involving the masseter muscle used for chewing and jaw clenching. Habits like bruxism, or chronic teeth grinding, can lead to muscle overuse and fatigue. The constant strain can cause the masseter muscle to become enlarged or inflamed. This results in a firm, tender appearance of the lower cheek and jaw angle on one or both sides, and is primarily a muscular issue.
Physical injury to the jawbone or surrounding soft tissue is another structural cause that can produce immediate, unilateral swelling. A direct blow to the face or jaw can cause a fracture, a bone bruise, or significant soft tissue trauma. The swelling is a natural bodily response to the injury, involving blood and inflammatory fluid rushing to the affected area. This type of swelling is accompanied by noticeable pain, bruising, and difficulty with normal jaw movement.
When to Seek Urgent Medical Attention
While many causes of jaw swelling are treatable in a routine setting, certain symptoms signal a rapidly spreading or severe infection that requires immediate attention. Any swelling that develops quickly or appears to be growing rapidly should be evaluated by a medical professional right away. The presence of a fever or chills accompanying the jaw swelling suggests the body is fighting a systemic or severe localized infection.
Difficulty breathing, labored breathing, or any change in your voice, such as a muffled or “hot potato” sound, indicate potential airway compromise. This can be a sign of a deep neck space infection, such as Ludwig’s angina, which spreads quickly and presses on the throat. Trouble swallowing, excessive drooling, or a restricted ability to open the mouth are also signs that a severe infection is affecting the floor of the mouth and neck tissues.
The onset of numbness or tingling in the jaw, lower lip, or chin (paresthesia) can indicate nerve involvement or damage due to infection or trauma. If the swelling is accompanied by a change in vision or confusion, this may signal that the infection has progressed beyond the local area. Any of these severe symptoms warrant an immediate visit to an emergency room to prevent the infection from blocking the airway or spreading.