Swelling inside the cheek, medically described as buccal swelling, can be a disconcerting experience. This symptom, which often presents as a localized lump or generalized puffiness, is frequently a temporary and harmless reaction to minor trauma or surface irritation. However, since the oral cavity is a gateway to deeper structures, swelling can signal infection or a systemic health issue, meaning professional diagnosis is necessary. The location and associated symptoms of the swelling provide significant clues to whether the issue is superficial or requires urgent medical attention.
Minor Injuries and Surface Inflammation
The inner cheek lining (buccal mucosa) is highly susceptible to small injuries that result in localized swelling. Accidental cheek biting (morsicatio buccarum) is a common cause where mechanical trauma causes the tissue to bruise and swell. This self-inflicted injury, often occurring during chewing, leads to a temporary inflammatory response as the body attempts to repair the damaged cells.
Canker sores (aphthous ulcers) are another frequent source of inner cheek swelling. While the defining feature is the painful open sore, the tissue immediately surrounding the ulcer often becomes inflamed and slightly raised as part of the body’s immune reaction. Mucoceles, small, fluid-filled cysts, also cause localized swelling, typically appearing as a soft, dome-shaped bump that can be clear or bluish. These cysts form when a minor salivary duct near the surface is damaged, often by trauma, causing saliva to leak into the surrounding connective tissue and accumulate.
Mucoceles are a common benign finding that often rupture and resolve within a few weeks. However, persistent habits like cheek chewing or sucking can cause them to recur, necessitating a visit to a dental professional.
Dental and Salivary Gland Concerns
Swelling that originates from deeper structures, such as the teeth or major salivary glands, tends to be more significant and painful. A dental abscess is a serious cause of inner cheek swelling, occurring when a bacterial infection in the tooth’s pulp tracks down to the root tip, forming a pocket of pus. The pus can then spread into the surrounding jaw bone and soft tissues, including the buccal space, leading to noticeable facial and internal cheek swelling.
Symptoms of an abscess often include severe, throbbing pain, sensitivity to hot or cold temperatures, and sometimes a fever, indicating a spreading infection. Following dental work (e.g., root canal or extraction), some localized swelling is an expected part of the healing process. This post-procedure swelling is temporary, in contrast to an infection where the swelling worsens over time and is accompanied by increasing pain or pus formation.
The parotid gland, located in the cheek area, is one of the three major salivary glands; its duct (Stensen’s duct) opens onto the inner cheek near the upper molars. Conditions affecting this gland can easily present as internal cheek swelling. Sialadenitis, a bacterial infection of the salivary gland, causes painful, hard swelling, often accompanied by fever and the drainage of pus into the mouth. A blockage in the duct (sialolithiasis or a salivary stone) can also cause swelling that is exacerbated during meals when saliva production increases.
Systemic Conditions and Urgent Medical Issues
While many causes of inner cheek swelling are localized, some less common conditions indicate a systemic problem or a rapidly progressing, urgent situation. Cellulitis is a severe bacterial skin infection that can occur on the face, spreading rapidly through the soft tissues and causing diffuse, warm, and tender swelling that extends beyond the initial site. When facial cellulitis is linked to a dental or oral source, it can quickly become life-threatening if the infection spreads to the neck or bloodstream.
A sudden, non-painful swelling of the inner cheek, lips, or tongue can be angioedema, which is rapid fluid accumulation in the deeper layers of the skin and mucous membranes. This is often triggered by an allergic reaction to food or medication, and requires immediate medical attention if the swelling progresses to affect the throat or airway.
Certain chronic conditions can also manifest with oral swelling, such as Sjögren’s syndrome, an autoimmune disorder affecting the moisture-producing glands. The inflammation associated with this condition can cause chronic or recurrent enlargement of the salivary glands, including the parotid gland in the cheek area. Any persistent, firm, or painless mass that does not resolve should be investigated by a healthcare professional, as some growths, including salivary gland tumors, may require monitoring.