Salivary gland problems that cause clinical symptoms include:
Obstruction: Obstruction to the flow of saliva most commonly occurs in the parotid and submandibular glands, usually because stones have formed. Symptoms typically occur when eating. Saliva production starts to flow, but cannot exit the ductal system, leading to swelling of the involved gland and significant pain, sometimes with an infection. Unless stones totally obstruct saliva flow, the major glands will swell during eating and then gradually subside after eating, only to enlarge again at the next meal. Infection can develop in the pool of blocked saliva, leading to more severe pain and swelling in the glands. If untreated for a long time, the glands may become abscessed.
It is possible for the duct system of the major salivary glands that connects the glands to the mouth to be abnormal. These ducts can develop small constrictions, which decrease salivary flow, leading to infection and obstructive symptoms.
Infection: The most common salivary gland infection in children is mumps, which involves the parotid glands. While this is most common in children who have not been immunized, it can occur in adults. However, if an adult has swelling in the area of the parotid gland only on one side, it is more likely due to an obstruction or a tumor.
Infections also occur because of ductal obstruction or sluggish flow of saliva because the mouth has abundant bacteria.
You may have a secondary infection of salivary glands from nearby lymph nodes. These lymph nodes are the structures in the upper neck that often become tender during a common sore throat. In fact, many of these lymph nodes are actually located on, within, and deep in the substance of the parotid gland or near the submandibular glands. When these lymph nodes enlarge through infection, you may have a red, painful swelling in the area of the parotid or submandibular glands. Lymph nodes also enlarge due to tumors and inflammation.
Tumors: Primary benign and malignant salivary gland tumors usually show up as painless enlargements of these glands. Tumors rarely involve more than one gland and are detected as a growth in the parotid, submandibular area, on the palate, floor of mouth, cheeks, or lips. An otolaryngologist-head and neck surgeon should check these enlargements.
Malignant tumors of the major salivary glands can grow quickly, may be painful, and can cause loss of movement of part or all of the affected side of the face. These symptoms should be immediately investigated.
Other Disorders: Salivary gland enlargement also occurs in autoimmune diseases such as HIV and Sjögren's syndrome where the body's immune system attacks the salivary glands causing significant inflammation. Dry mouth or dry eyes are common. This may occur with other systemic diseases such as rheumatoid arthritis. Diabetes may cause enlargement of the salivary glands, especially the parotid glands. Alcoholics may have salivary gland swelling, usually on both sides.