Swelling of the inner cheek, or buccal mucosa, is a common symptom ranging from a minor annoyance to an indication of an underlying health issue. The mouth’s inner lining is delicate tissue constantly exposed to mechanical forces, chemicals, and microorganisms, making it susceptible to irritation and inflammation. While swelling can be concerning, most causes are localized and temporary, often resolving without intervention. Understanding the origins of the inflammation helps determine the appropriate course of action.
Physical Trauma and Local Irritants
The most frequent causes of inner cheek swelling involve mechanical injury or direct irritation. Accidental biting, known as morsicatio buccarum, is a common self-inflicted trauma where the cheek tissue is caught between the teeth, leading to immediate inflammation and tenderness. Repeated trauma can sometimes result in a localized, raised area of hardened tissue called a fibroepithelial polyp, which forms as a healing response.
Irritation from dental appliances also frequently causes swelling where the device rubs against the soft lining of the mouth. Braces, retainers, or poorly fitting dentures create continuous friction, leading to inflammation. Sharp edges from a broken tooth or a chipped filling can similarly abrade the inner cheek, causing localized swelling and ulceration.
Certain substances can also act as local irritants, triggering an inflammatory response. Consuming highly acidic foods, spicy items, or very hot liquids can cause chemical or thermal burns that result in immediate swelling and discomfort. Trauma can also disrupt a minor salivary gland duct, leading to a mucocele, which is a harmless, fluid-filled sac appearing as a soft, localized swelling.
Infections and Ulcerations
When swelling is accompanied by pain, redness, or distinct lesions, a localized infection or ulcer is likely. The most common lesions are aphthous ulcers, or canker sores, which present as small, painful, white or yellowish sores surrounded by a red halo. These ulcers cause localized swelling and typically heal within one to two weeks, often connected to minor trauma, stress, or nutritional deficiencies.
A more concerning cause is an oral abscess, typically originating from a dental problem like a cracked tooth or untreated cavity. When bacteria penetrate the tooth’s pulp, the infection spreads into the surrounding soft tissues, causing painful, localized swelling inside the cheek near the tooth root. This deep bacterial invasion requires prompt dental intervention to prevent the infection from spreading.
Localized viral infections can also manifest as lesions and swelling. The herpes simplex virus, which causes cold sores, can result in small, blister-like sores on the buccal mucosa that rupture and cause swelling. Fungal infections, such as oral thrush (Candida albicans), may cause white patches and generalized inflammation, particularly in individuals with weakened immune systems or those taking antibiotics.
Salivary Gland and Systemic Causes
Some causes of inner cheek swelling relate to the salivary glands or larger systemic conditions. The parotid gland, a major salivary gland located near the cheek, can cause swelling when blocked or infected. Sialolithiasis occurs when calcified stones form in the salivary ducts, obstructing saliva flow and causing the gland to swell painfully, especially when eating.
Sialadenitis, a bacterial infection of the salivary gland, results in a firm, tender swelling, usually on one side of the face. Systemic viral infections, such as mumps, cause bilateral swelling of the parotid glands, resulting in puffy cheeks, often accompanied by fever and headache. Swelling may also result from sialadenosis, a non-inflammatory enlargement of the parotid glands often associated with systemic issues like diabetes or chronic alcohol use.
Less commonly, inner cheek swelling can manifest due to a systemic inflammatory or autoimmune disorder. Sjögren’s syndrome is an autoimmune condition that attacks moisture-producing glands, leading to dry mouth and chronic salivary gland swelling. A severe allergic reaction, known as angioedema, causes rapid swelling of the deeper layers of mucosal tissue, potentially affecting the inner cheeks, lips, and tongue.
Recognizing Red Flags and Seeking Care
While most instances of inner cheek swelling are benign and self-limiting, certain signs should prompt a visit to a medical or dental professional. Swelling that persists for more than seven to ten days without improvement requires professional evaluation, especially if the cause is not obvious minor trauma. A painless lump or a sore that does not heal should also be examined to rule out serious conditions.
Immediate medical attention is necessary if the swelling is accompanied by specific systemic symptoms. These include a high fever, difficulty breathing or swallowing, or swelling that rapidly spreads to the neck or face. The presence of numbness, tingling, or a change in facial movement alongside the swelling is also an urgent concern. These symptoms may suggest a rapidly spreading infection or a severe underlying systemic issue requiring immediate diagnosis.