Swollen salivary glands are most often caused by salivary stones, infections, or an autoimmune condition called Sjögren’s disease. Less common causes include tumors, metabolic disorders linked to diabetes or heavy alcohol use, and viral infections like mumps. The swelling can affect any of your three major salivary gland pairs, but the parotid glands (located just in front of each ear) are the most frequently involved.
Salivary Stones
Salivary stones, known medically as sialoliths, are the most common cause of a single swollen salivary gland. These small, hardened deposits form inside the ducts that carry saliva from the gland to your mouth. They’re made mostly of calcium-based minerals, along with a mix of proteins, bacteria, and cellular debris. When a stone blocks the duct, saliva backs up behind it, and the gland swells, often painfully, especially during meals when saliva production ramps up.
The swelling from a stone tends to come and go at first. You might notice it flare during eating and then settle down afterward. Over time, a blocked duct can become infected, turning an intermittent nuisance into something more urgent with redness, warmth, and pus draining into the mouth. Risk factors for stones include dehydration and medications that reduce saliva flow, such as diuretics, antihistamines, and certain antidepressants.
CT scans are the most reliable way to detect stones, with a sensitivity of about 98%. Ultrasound catches only about 65% of stones and tends to miss smaller ones located in the duct under the tongue. Many stones can be managed conservatively with hydration, warm compresses, and gentle massage of the gland. Larger or stubborn stones sometimes require a minimally invasive procedure to remove them.
Bacterial Infections
A bacterial infection of the salivary gland, called sialadenitis, causes rapid-onset swelling along with pain, redness, and sometimes a foul-tasting discharge of pus into the mouth. The most common culprit is Staphylococcus aureus. These infections tend to develop when saliva flow is already reduced, because saliva normally flushes bacteria out of the ducts. Anything that dries out your mouth, whether it’s dehydration after surgery, certain medications, or a blocked duct, creates the conditions bacteria need to take hold.
Bacterial sialadenitis is more common in older adults and in people who are hospitalized or have weakened immune systems. The swelling is typically one-sided and worsens over hours to days. If you press on the swollen gland, you may see pus come out of the duct opening inside your mouth. Treatment usually involves antibiotics, increased fluid intake, and measures to stimulate saliva flow like sour candies or gentle gland massage.
Viral Infections
Mumps is the classic viral cause of salivary gland swelling, producing puffy, tender parotid glands on both sides of the face. The swelling typically peaks within one to three days and then gradually subsides over the following week, with most cases resolving within 10 days. Unlike bacterial infections, viral parotitis doesn’t produce pus and affects both sides in the majority of cases.
Other viruses can also inflame the salivary glands, including HIV, influenza, and certain herpes viruses. Viral swelling is sometimes confused with swollen lymph nodes in the neck. The key difference: swollen lymph nodes have well-defined borders and sit behind the angle of the jawbone, while parotid swelling pushes the earlobe outward and obscures the jawline.
Sjögren’s Disease
Sjögren’s disease is an autoimmune condition in which the immune system attacks moisture-producing glands, including the salivary and tear glands. The result is chronic dry mouth, dry eyes, and recurrent or persistent salivary gland swelling, usually in the parotid glands on both sides. The swelling tends to be gradual and may wax and wane over months or years.
Sjögren’s is diagnosed through a combination of blood tests and functional measurements. The two most significant findings are the presence of a specific antibody called anti-SSA (Ro) and evidence of immune cells infiltrating the salivary gland tissue on biopsy. Doctors also measure how much saliva you produce in a set time period and assess tear production and eye surface damage. People with Sjögren’s produce dramatically less saliva than normal, often below 0.1 milliliters per minute, compared to the typical resting flow of 0.3 to 0.5 milliliters per minute. The condition is far more common in women and often coexists with other autoimmune disorders like rheumatoid arthritis or lupus.
Metabolic Causes
Not all salivary gland swelling involves infection or obstruction. A condition called sialadenosis causes painless, bilateral enlargement of the parotid glands without any inflammation. The glands simply get bigger, sometimes noticeably changing the shape of the face. This type of swelling is linked to metabolic disturbances, particularly chronic alcohol use and diabetes.
Alcoholism is one of the primary drivers of sialadenosis. The exact mechanism isn’t fully understood, but chronic alcohol exposure appears to cause fatty changes and enlargement of the gland cells themselves. Diabetes, malnutrition, eating disorders like bulimia, and thyroid dysfunction can produce similar changes. Because the swelling is painless and develops slowly, people with sialadenosis sometimes live with it for months or years before seeking evaluation.
Salivary Gland Tumors
A slowly growing, painless lump in a salivary gland may be a tumor. The majority of salivary gland tumors are benign. The most common type, called pleomorphic adenoma, accounts for 45% to 75% of all salivary gland tumors and grows very slowly, typically enlarging only one to two centimeters over several years. About 84% of these tumors develop in the parotid gland.
Malignant salivary gland tumors are less common but do occur. Warning signs that a growth may be cancerous include rapid enlargement, pain, and facial nerve problems like numbness or weakness on one side of the face. One type of cancer, carcinoma ex pleomorphic adenoma, develops within a longstanding benign tumor that suddenly starts growing faster. Any new, persistent lump in a salivary gland warrants evaluation, even if it’s painless, because imaging and sometimes a needle biopsy are needed to distinguish benign from malignant growths.
Duct Narrowing and Other Causes
Strictures, or scar-like narrowing of the salivary ducts, can mimic the symptoms of a stone. They block saliva flow and cause intermittent swelling, particularly at mealtimes. Strictures sometimes develop after an infection, after radiation therapy to the head and neck, or without a clear cause. They’re diagnosed with imaging or a tiny scope inserted into the duct.
Certain medications and environmental exposures can also trigger gland swelling. Drugs that drastically reduce saliva production, including some blood pressure medications, antidepressants, and antihistamines, create conditions that make both stones and infections more likely. Radiation therapy targeting the head or neck area can inflame and damage the glands directly, sometimes producing swelling that persists long after treatment ends.
What the Swelling Pattern Tells You
The pattern of swelling offers useful clues about the cause. One-sided swelling that comes and goes with meals points toward a stone or stricture. One-sided swelling with pain, redness, and fever suggests a bacterial infection. Painless swelling on both sides that develops gradually is more consistent with Sjögren’s disease, sialadenosis, or a systemic condition. A single firm, slow-growing lump that doesn’t fluctuate with eating raises the possibility of a tumor.
Swelling that makes it hard to breathe or swallow is a medical emergency. Otherwise, salivary gland swelling that persists for more than a week or two, keeps coming back, or is accompanied by fever, pus, or facial numbness deserves prompt evaluation. Ultrasound is usually the first imaging test ordered, with CT reserved for cases where stones are suspected but not visible on ultrasound or when a more detailed look at the gland is needed.