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High Yield Notes
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Content Reviewers:

Rishi Desai, MD, MPH

“Sial” refers to saliva, “aden” refers to a gland, and “itis” is inflammation, so acute sialadenitis is the sudden inflammation of any of the salivary glands, the major ones being the parotid, submandibular and sublingual gland.

Sialadenitis usually affects a single parotid gland rather than both, and is most common among individuals in their 50s and 60s but can happen at any age, even in a newborn.

Acute sialadenitis is most often caused by the bacteria Staphylococcus aureus, but may also be caused by Streptococcus viridans, or by Haemophilus influenzae, as well as viruses like mumps and HIV.

When it’s a bacterial infection, it often starts up after a salivary duct is plugged up by a salivary stone.

Salivary glands secrete saliva through tiny ducts in the mouth, to help lubricate the inside of the mouth and also moisten and soften food.

The antibacterial properties of saliva and the quick flow through the salivary duct both help to prevent infections from developing.

But there are various factors that reduce the rate of salivary flow, like dehydration, illness, and certain medications. These factors can allow deposits to settle in the walls of the salivary duct, physically blocking the path and further slowing down the flow of saliva.

This can allow tiny areas of stagnation where more deposits of calcium, phosphorous, and other electrolytes can precipitate out, ultimately forming small concretions called microsialoliths, or tiny salivary stones.

Over time, these can grow into sialoliths which are larger salivary stones.

Salivary stones block up the duct, which allows bacteria to move from the mouth up and around the blockage and into the salivary duct.

And this results in inflammation and tissue swelling which can further compress the salivary duct, and worsen the problem.

Acute sialadenitis causes pain and swelling as well as redness of the skin overlying the affected gland.

Because the salivary gland is affected, it also means that less saliva is being made which dries out the mouth, and can cause a bad taste in the mouth from pus leaking out of the affected duct.


Sialadenitis is an inflammation of the salivary glands, which are glands that produce saliva to help moisten and protect the mouth and digestive system. Sialadenitis can occur due to bacterial or viral infections, blockages in the ducts that carry saliva from the glands, or radiation exposure.

Sialadenitis can be acute or chronic. Acute sialadenitis is typically caused by a bacterial infection like Staphylococcus aureus, which can get established when a salivary duct is plugged up by a salivary stone. Chronic sialadenitis is generally associated with decreased salivary flow, which might be caused by salivary duct fibrosis after an acute infection, or an autoimmune process.

Common symptoms of sialadenitis include pain and swelling in the affected gland, difficulty opening the mouth, and a decreased ability to produce saliva. Sometimes there may be redness, tenderness, and a fever. Diagnosis is generally based on identifying a swollen salivary gland, and a laboratory culture of pus collected from the glands. Imaging can also be helpful to check for an abscess, salivary stone, or tumor. Treatment depends on the underlying cause but may include hydration, glandular massage to stimulate salivary flow, and antibiotics to treat an infection.