A tooth infection can cause the lymph nodes in the head and neck to swell. This reaction is an expected sign that the body’s defense system is actively working to contain an infection originating from the mouth. Lymph nodes are small, bean-shaped glands that function as filtering stations for lymphatic fluid, collecting waste and pathogens from tissues. When bacteria from an infection, such as an abscess or deep decay, spread beyond the tooth, they trigger this systemic response. The activation of these nodes establishes a clear connection between a localized oral health problem and a visible physical manifestation of immune status.
The Immune Response: Why Lymph Nodes Swell
When harmful bacteria from a dental infection leak into the surrounding tissue, they are picked up by the lymphatic vessels. These vessels transport the fluid, which contains the pathogens, to the nearest lymph nodes. The nodes act as a checkpoint, trapping the bacteria and filtering the fluid before it returns to the bloodstream.
Inside the lymph node, specialized immune cells, particularly lymphocytes, rapidly multiply to mount a targeted defense. This proliferation of immune cells within the confined space causes the node to physically enlarge, resulting in the tender, palpable swelling known as lymphadenopathy. This physiological mechanism is a protective measure designed to prevent the infection from spreading further into the body. The size and tenderness of the swollen node often correlate directly with the severity of the underlying dental infection.
Locating Swollen Lymph Nodes from Dental Issues
The location of the swelling helps pinpoint the source of the oral infection because lymph fluid drains predictably through specific chains of nodes. Dental infections most commonly affect the nodes closest to the jawline and neck. The primary nodes involved are the submental, submandibular, and upper deep cervical chains.
The submental nodes, located under the chin, often drain the lower front teeth, the tip of the tongue, and the lower lip. The submandibular nodes, found along the inner curve of the lower jawbone, drain the majority of the teeth, the floor of the mouth, and the cheeks. An infection in a molar or premolar is likely to cause swelling in this submandibular area.
You can check these areas by gently pressing or palpating them with your fingertips. Normal lymph nodes are usually not detectable or are soft and small. When inflamed, they may feel like firm, tender, or movable lumps under the skin. If the swelling is noticeably larger or more tender on one side, it suggests the dental infection is on that same side of the mouth.
When Swollen Nodes Indicate a Dental Emergency
While minor swelling of a lymph node is a routine sign of an immune response, certain accompanying symptoms signal that the dental infection has progressed into a serious and potentially life-threatening emergency. Rapidly worsening swelling, especially if it extends into the face, jaw, or neck, is a major warning sign of a spreading infection like cellulitis. This bacterial infection of the skin and underlying tissues requires immediate medical intervention.
Systemic symptoms indicate that the infection has broken past the local defenses and is now affecting the entire body. These symptoms include a fever of 100.4°F (38°C) or higher, chills, and general fatigue.
Difficulty breathing or swallowing, inability to fully open the mouth, or a change in voice should be treated as an an urgent medical situation. If these severe symptoms are present, a visit to a medical doctor or an emergency room is necessary to manage the systemic infection, which may require intravenous antibiotics. While a dentist must ultimately treat the original source of the infection, the immediate priority is controlling the rapidly spreading or systemic symptoms to prevent complications like sepsis or airway obstruction.