Sialadenitis: Salivary Gland Infection Explained

Editorially reviewed by the Dental.me Editorial Team · Updated July 2026

A tender, swollen lump on your cheek or under your jaw that gets worse when you eat, sometimes paired with a foul taste in your mouth, is a classic sign of a salivary gland infection. The medical name is sialadenitis, and it happens when one of the glands that make your saliva becomes inflamed or infected. It can be uncomfortable and, if ignored, can spread, but most cases respond well to prompt treatment. Here is a plain-English guide to what sialadenitis is, why it happens, how it is treated, and when it becomes an emergency.

What Is Sialadenitis?

Sialadenitis is inflammation or infection of a salivary gland. You have several salivary glands, and three major pairs do most of the work: the parotid glands (in front of and slightly below each ear, over the cheek), the submandibular glands (under the jaw), and the sublingual glands (under the tongue). These glands produce saliva and send it into your mouth through small tubes called ducts.

Sialadenitis most often affects the parotid gland or the submandibular gland. Saliva does more than moisten food. It rinses the mouth, carries away bacteria, and keeps the whole system flowing. When saliva production drops or a duct gets blocked, that natural rinsing slows down. Bacteria that normally live in the mouth can then travel up the duct and multiply inside the gland, causing a bacterial infection. Viruses can inflame the glands too. The result is a gland that is swollen, painful, and sometimes leaking pus.

Symptoms of a Salivary Gland Infection

Symptoms usually appear on one side and can come on over hours to a day or two. Common signs include:

• Painful swelling of the gland, felt as a lump on the cheek (parotid) or under the jaw (submandibular)
• Tenderness and redness over the swollen area, which may feel warm
• A bad or foul taste in the mouth, often from pus draining out of the duct
• Reduced saliva or dry mouth, sometimes with pus you can express near the duct opening
• Fever and chills when the infection is bacterial
• Difficulty opening the mouth or eating because of pain and swelling
• Swelling that worsens with eating, since food and even the thought of food stimulate saliva that cannot drain past a blockage

That last point is a useful clue. Pain and swelling that flare right around mealtimes point toward the salivary system rather than a general facial swelling.

What Causes a Salivary Gland Infection?

The single biggest driver is anything that slows saliva flow. When saliva moves freely, it keeps ducts flushed and bacteria out. When flow drops, bacteria get a foothold. Common causes and risk factors include:

• Dehydration and reduced saliva flow – the most common trigger, especially after illness, surgery, or simply not drinking enough
• Salivary gland stones that block a duct, trapping saliva behind them. A blocked duct is a frequent setup for infection; you can read more about salivary gland stones and how they form
• Dry mouth from medications, radiation, or aging. Chronic dry mouth (xerostomia) lowers the natural rinsing that protects the glands
• Autoimmune conditions such as Sjogren’s syndrome, which directly reduces saliva. See our guide to dry mouth and Sjogren’s syndrome
• Poor oral hygiene, which raises the bacterial load in the mouth
• Recent illness or surgery, when people are dehydrated and less mobile
• A weakened immune system, which makes infection easier to take hold

The Viral Form: Mumps and Others

Not every case is bacterial. Viruses can inflame the salivary glands, and mumps is the classic example, causing swelling of the parotid glands on one or both sides. Mumps is far less common where vaccination is routine, but it still occurs, and other viruses can inflame the glands as well. Viral sialadenitis is generally managed with supportive care rather than antibiotics, which is one reason a proper diagnosis matters.

How Sialadenitis Is Diagnosed and Treated

A dentist or doctor can often recognize sialadenitis from the exam alone by feeling the swollen gland, checking for pus at the duct opening, and asking about your symptoms and history. When more detail is needed, imaging such as an ultrasound or CT scan can look for a stone, an abscess, or a duct blockage. If pus is present, a culture can identify the bacteria and guide antibiotic choice.

Treatment depends on the cause. For bacterial sialadenitis, care usually combines antibiotics with steps that get saliva flowing and clear the gland:

• Antibiotics prescribed by a clinician to clear the bacterial infection
• Hydration – drinking plenty of fluids to boost saliva volume
• Warm compresses over the gland to ease pain and encourage drainage
• Gentle gland massage toward the duct to help move saliva and pus out
• Sialagogues – sour or tart sugar-free candies, or a squeeze of lemon, to stimulate saliva
• Good oral hygiene to lower the bacterial load
• Pain and fever relief as recommended by your clinician

If a stone or other blockage is behind the infection, treating that blockage, sometimes by removing the stone, is part of resolving the problem and preventing a repeat. Viral cases are managed with rest, fluids, and comfort measures. With prompt treatment, most cases of sialadenitis improve within a few days.

Red Flags: When It Becomes Urgent

Most salivary gland infections settle with prompt care, but some situations need medical attention right away. Seek urgent care if you notice:

• A pocket of pus, or abscess, forming in or around the gland – this often needs to be drained
• High fever or worsening chills
• Rapidly spreading swelling in the face or neck
• Difficulty breathing or swallowing
• Severe, unrelenting pain

An untreated infection can spread beyond the gland, so these warning signs are not something to wait out. If you are unsure how serious your symptoms are, our guide to what counts as a dental emergency can help you decide when to be seen quickly.

Preventing Salivary Gland Infections

Because reduced saliva flow is at the heart of most cases, prevention centers on keeping saliva moving and the mouth clean:

• Stay well hydrated, especially when you are sick, recovering from surgery, or in hot weather
• Maintain good oral hygiene with regular brushing and flossing
• Stimulate saliva with sugar-free gum or tart sugar-free candies if your mouth tends to run dry
• Manage dry-mouth causes with your doctor, including reviewing medications and treating conditions like Sjogren’s
• Treat salivary stones promptly so ducts stay open

The Dental Connection and When to See Someone

Dentists are often the first to spot a salivary gland problem, since they examine the mouth and jaw closely and can help manage the oral factors that contribute to it, such as hygiene and dry mouth. That said, a spreading or severe infection is a medical issue and may need a physician, imaging, or drainage.

It also helps to know what sialadenitis is not. A simple salivary stone can cause swelling around meals without infection, at least at first, which is why classic mealtime swelling without fever points more toward a stone than an active infection. And a salivary gland infection is different from a tooth abscess, which starts in a tooth and produces a different pattern of pain and swelling. Getting the right diagnosis points you to the right treatment.

The takeaway: sialadenitis is a painful salivary gland infection, most often driven by dehydration, reduced saliva flow, or a blocked duct. Bacterial cases are treated with antibiotics plus hydration, warm compresses, gentle massage, and saliva stimulation, and most improve quickly. Watch for red flags like an abscess or spreading swelling, which need urgent care. Staying hydrated and keeping good oral hygiene go a long way toward prevention, and if the gland stays swollen, painful, or feverish, see a dentist or doctor rather than waiting it out.

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