A swollen left cheek is a noticeable symptom that can stem from various underlying issues. Swelling on one side of the face points to a localized problem originating from inside the mouth, the skin, or the salivary glands. Causes range widely, from a common dental infection to a severe allergic reaction or a systemic illness. Understanding the characteristics of the swelling, such as its speed of onset and associated symptoms, provides important clues about its origin. This information provides general context regarding possible causes and should not substitute for professional medical evaluation.
Common Dental and Gum-Related Causes
Infections originating in the teeth and gums are one of the most frequent causes of unilateral cheek swelling. The close proximity of the teeth to the soft tissues of the cheek allows bacterial infections to spread easily. A dental abscess, a collection of pus caused by a bacterial infection, can form at the root tip (periapical) or in the gum pocket (periodontal). This localized infection often causes a throbbing toothache and sensitivity before the swelling becomes externally visible on the cheek.
Another common source of swelling is pericoronitis, the inflammation of the gum tissue surrounding a partially erupted tooth, most frequently a wisdom tooth. When a wisdom tooth is partially visible, a flap of gum tissue can trap food and bacteria, leading to infection. This results in pus, pain that radiates to the ear or throat, and noticeable swelling in the jaw and cheek area. If the infection progresses, it can lead to trismus, the painful restriction of the ability to open the mouth fully.
Infections of the Skin and Salivary Glands
Swelling not related to the teeth may involve the soft tissues of the face or the major salivary glands located in the cheek region. Facial cellulitis is a bacterial skin infection that causes a diffuse, warm, red, and rapidly spreading swelling of the soft tissues beneath the skin. This condition often originates from an untreated dental abscess, as bacteria spread from the localized infection into the face.
The parotid gland, the largest of the salivary glands, sits in front of the ear and extends over the masseter muscle near the cheek. Inflammation of this gland, known as parotitis, can be caused by viral infections, such as mumps, or by bacterial infections. If the cause is bacterial, the swelling is often confined to one side of the face, accompanied by fever and pain.
A separate cause involving the salivary glands is sialolithiasis, the formation of stones within the ducts. These stones block the flow of saliva, causing the gland to swell and become painful, particularly around mealtimes when saliva production increases. This swelling is typically unilateral, affecting the cheek area where the parotid gland is located.
Acute Injury and Allergic Reactions
Sudden, acute swelling can result directly from external factors, such as trauma or an immune response. A direct blow, fall, or sports injury to the face causes immediate inflammation and bruising. This swelling is usually accompanied by localized pain and is easily identifiable due to the preceding event. In severe cases, swelling may indicate an underlying bone fracture, such as a fractured cheekbone, which requires immediate medical imaging.
Allergic reactions can trigger angioedema, a condition involving swelling in the deeper layers of the skin, often affecting the cheeks, lips, or eyelids. This reaction can be caused by exposure to a food allergen, medication, or an insect bite or sting, with swelling developing rapidly. Swelling from angioedema is often non-pitting and may be associated with hives. Certain blood pressure medications, such as ACE inhibitors, can also cause angioedema without an immediate allergic trigger.
When Swelling Requires Immediate Medical Care
While many causes of cheek swelling are treatable in an outpatient setting, certain symptoms indicate a spreading or severe infection requiring emergency intervention. The inability to fully open the mouth (trismus) or any difficulty with breathing or swallowing (dysphagia) suggests that the swelling is encroaching on the airway. This is a potentially life-threatening situation.
Rapidly spreading swelling, especially if accompanied by a high fever, chills, or a feeling of severe illness, signals that the infection has become systemic. A specific concern is Ludwig’s angina, a severe form of cellulitis that affects the floor of the mouth and can quickly obstruct the airway. Any swelling that extends to the neck or the floor of the mouth, or causes vision changes, must be treated as a medical emergency. Seeking immediate care is the safest course of action when these severe warning signs are present.