Sialolithiasis is the formation of calcified stones inside the salivary glands or their ducts. These stones, called sialoliths, block the normal flow of saliva into the mouth, causing swelling and pain that typically flare up during meals. It is the most common cause of salivary gland obstruction and accounts for the majority of salivary gland diseases in middle-aged adults.
How Salivary Stones Form
Your mouth has three pairs of major salivary glands: the submandibular glands (under the jaw), the parotid glands (in front of the ears), and the sublingual glands (under the tongue). Each gland drains saliva through a duct into your mouth. When saliva flow slows or stagnates, minerals like calcium and phosphate can start to crystallize around a small core of debris, gradually building up into a stone. These stones range in size from a grain of sand to well over a centimeter.
About 85% of salivary stones form in the submandibular gland, and that lopsided number comes down to anatomy and chemistry. The submandibular duct runs upward against gravity to reach its opening under the tongue, which naturally slows drainage. The saliva this gland produces is also thicker and more alkaline than what the parotid gland produces, making it easier for minerals to fall out of solution and clump together. The parotid gland accounts for roughly 15% of cases, while fewer than 5% of stones appear in the sublingual or minor salivary glands.
What It Feels Like
The hallmark symptom is swelling and pain in the affected gland that gets worse when you eat or even think about food. This happens because eating triggers a surge of saliva production. If a stone is blocking the duct, that saliva has nowhere to go, and the gland swells like a balloon. The swelling usually peaks during meals and then gradually subsides over the next hour or two as saliva slowly seeps around the stone.
When a stone only partially blocks the duct, symptoms can come and go for weeks or months. You might notice a dull ache under your jaw or a strange fullness that appears at mealtimes and fades between them. In more complete blockages, the gland stays swollen and tender, and you may notice a foul taste in your mouth if the trapped saliva becomes infected. A firm lump can sometimes be felt under the tongue or along the inner cheek.
Risk Factors
Anything that reduces saliva flow or changes saliva composition raises the odds of stone formation. Dehydration is a major contributor: when your body is low on fluids, saliva becomes more concentrated with minerals. Medications that dry out the mouth, including certain antihistamines, antidepressants, and diuretics, can have the same effect by reducing saliva output.
Smoking is the best-studied lifestyle risk factor. A large Korean case-control study found that smokers had about 31% higher odds of developing sialolithiasis compared to nonsmokers, and longer smoking duration increased the risk further. Stones in current smokers also tend to be physically larger than those in former smokers. Alcohol and obesity, by contrast, have not shown a clear statistical link to stone formation. A history of previous salivary gland infections also appears to set the stage for stones: in one study, 90% of patients with sialolithiasis had a prior episode of gland inflammation.
How It Is Diagnosed
Doctors often suspect sialolithiasis based on the classic pattern of mealtime swelling and pain. A physical exam can sometimes reveal the stone as a hard lump along the duct. Imaging confirms the diagnosis and pinpoints the stone’s location.
Ultrasound is the typical first step because it is quick, painless, and involves no radiation. It detects salivary stones with a sensitivity of about 72%. Sialography, where contrast dye is injected into the duct and X-rays are taken, picks up stones about 87% of the time. The most accurate method is sialoendoscopy, a tiny camera threaded directly into the duct, which detects stones in virtually 100% of cases and can often treat them at the same time. CT scans are also used, particularly when a stone is suspected deep within the gland tissue.
Treatment Options
Small stones sometimes pass on their own. Drinking plenty of water, sucking on sour candy or citrus drops to stimulate saliva flow, and gently massaging the gland toward the duct opening can help flush a stone out. Warm compresses over the swollen area also encourage drainage. This approach works best for stones in the duct (rather than deep in the gland) that are only a few millimeters across.
When stones are too large or too firmly lodged to pass naturally, minimally invasive procedures are the next step. Sialoendoscopy allows a surgeon to look inside the duct with a miniature scope and extract the stone using tiny baskets or forceps. Stones between 3 and 5 millimeters that are still mobile can be retrieved this way with success rates above 80%. However, only about 15 to 20% of stones are small and loose enough to be pulled out whole. The rest need to be broken apart first or addressed with a different technique.
Extracorporeal shock wave lithotripsy (ESWL) uses focused sound waves to shatter stones into fragments small enough to wash out naturally. It works particularly well for parotid gland stones and for submandibular stones smaller than 7 millimeters that sit deep in or near the gland. Complete stone clearance rates with ESWL range from about 26% to 81%, with better results for parotid stones than submandibular ones. For the roughly 10 to 20% of stones that cannot be reached by a scope or broken up externally, ESWL under ultrasound guidance can still succeed in up to 80% of cases.
In severe or recurrent cases, especially when the stone is large, deeply embedded, or has caused repeated infections, surgical removal of the entire gland may be necessary. This prevents further complications like chronic infection or permanent gland damage. Gland removal is generally a last resort after less invasive options have been exhausted.
Complications of Untreated Stones
A salivary stone that stays in place creates a breeding ground for bacteria. Saliva pools behind the blockage, and the stagnant fluid can become infected, leading to sialadenitis, a painful inflammation of the gland. Repeated infections can progress to abscess formation, where pus accumulates within the gland tissue. A submandibular abscess is a serious condition that typically requires drainage and sometimes emergency gland removal. Over time, chronic obstruction and recurrent infection can cause permanent scarring and shrinkage of the gland, reducing its ability to produce saliva even after the stone is removed.
Recurrence and Prevention
After a stone is successfully removed, the recurrence rate ranges widely, from as low as 0.5% to as high as 19%, depending on the location, the removal method, and how long patients are followed. One study tracking patients after deep stone removal from the submandibular duct found that about 8.6% developed a new stone requiring a second procedure. When a second surgery is needed, the risk of yet another recurrence drops considerably.
Staying well hydrated is the single most practical step you can take to reduce your risk of forming new stones. Higher fluid intake keeps saliva dilute and flowing freely, making it harder for minerals to crystallize. If you smoke, quitting removes a significant and well-documented risk factor. If you take medications known to cause dry mouth, talk to your prescriber about alternatives or use sugar-free lozenges to keep saliva moving throughout the day. Paying attention to early warning signs, like mild mealtime swelling, and seeking treatment before full obstruction sets in can help prevent the cycle of infection and scarring that makes recurrence more likely.