What is Parotitis? Causes of Inflamed Parotid Gland

Parotitis is the term for inflammation of the parotid gland, the largest of the salivary glands located on both sides of the face near the angle of the jaw and just below the ear. Most acute cases are due to an infection, particularly bacterial or viral, whereas chronic cases may be due to various other causes like an infection, autoimmune disorders, medication or even tumors. Parotitis may arise on one or both sides (unilateral or bilateral) and feature with swelling of the parotid gland, dry mouth, drooling and pain.

There are various causes of parotid gland swelling or enlargement that may not be related to inflammation. Therefore a swollen parotid gland may not always be parotitis and all the possible causes need to be investigated. Read more on swollen salivary glands.

Causes of Parotitis

The causes of parotitis can be divided into infectious and non-infectious causes. Most infections are acute but chronic infections are almost always due to underlying factors like immune deficiency, persistent dry mouth and malignancies.


Most infectious cases of parotitis are due to bacteria or viruses. Fungal infections are extremely rare and more likely to be seen in HIV infection and less frequently in uncontrolled diabetes mellitus (sugar diabetes). Infectious parotitis can be acute or chronic.

Acute bacterial parotitis is the more common infectious cause of parotid gland inflammation. It is often associated with acute causes of mouth dryness, particularly with dehydration, or may arise as a complication of an orodental condition. Chronic bacterial parotitis is more common in the elderly, with the use of chronic medication that causes a pronounced dry mouth,  HIV positive patients and diabetes mellitus. In the chronic setting, it is more often a case of recurrent bacterial infections rather than a persistent infection. Tuberculosis (TB) may also be a cause of long term infectious parotitis.

Mumps is the most common viral cause of parotitis and is usually acute. Although once considered as a common childhood disease, it is seen less frequently with the introduction of immunization in children. Chronic cases of viral parotitis is almost always seen with HIV infection. However, not every case of parotitis in a person who is HIV positive is related to an infection.


Injury to the parotid gland may be either mechanical or chemical. Mechanical trauma may be seen with a blow especially if there is a fracture of the mandible, following surgery to the mouth or face and with certain dental procedures. Chemical trauma is more often drug induced where certain medication is toxic to the parotid gland tissue. Alcohol abuse may also be a cause although enlargement of the parotid gland may be unrelated to inflammation in long term alcoholism.


Autoimmune parotitis is due to the action of the body’s immune system against the parotid gland tissue. It may be related to Sjogren’s syndrome where other glands and tissues are also involved, leading to characteristic symptoms like dry mouth, dry eyes and conjunctivitis (inflammation of the conjunctiva of the eye) along with parotitis. Not every case of autoimmune parotitis is associated with Sjogren’s syndrome but the disease process affecting the parotid gland is often the same.

Other Causes of Parotitis

  • Salivary stone (sialolithiasis)
  • Medication
  • Tumors
  • Salivary duct defects or strictures
  • Eating disorders like bulimia
  • Certain spicy food
  • Emotional stress
  • Excessive caffeine intake

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