The glands you can feel under your jaw are primarily submandibular salivary glands, one on each side. These walnut-sized glands produce saliva and sit just beneath the jawbone. But they’re not the only structures in that area. A cluster of small lymph nodes, part of your immune system, also lives in the same space. When something feels swollen or tender under your jaw, it’s usually one of these two types of glands reacting to something.
Submandibular Salivary Glands
Your submandibular glands are two of the three pairs of major salivary glands in your head. Together, the two glands are roughly the size of a walnut, tucked just inside the curve of your lower jawbone on each side. They connect to your mouth through a duct that opens under your tongue.
These glands are saliva factories. Your salivary glands collectively produce one to two liters of saliva every day. That saliva does more than keep your mouth wet. It contains enzymes that start breaking down starches before food even reaches your stomach, rinses bacteria off your teeth to prevent cavities, and lubricates food so it’s easier to swallow. The parotid glands (in front of your ears) produce about half of your total saliva, but the submandibular glands handle a significant share of the rest, and they produce a thicker, more mineral-rich saliva than the other glands.
Submandibular Lymph Nodes
Sitting right alongside the salivary glands, and sometimes difficult to distinguish from them by touch, are the submandibular lymph nodes. These are small, bean-shaped filters that trap bacteria, viruses, and other debris draining from your face, teeth, gums, tongue, and floor of your mouth. When they’re doing their job quietly, they’re soft and barely noticeable, typically under 9 millimeters across (smaller than a centimeter).
When you’re fighting an infection, like a cold, a sore throat, or a dental problem, these lymph nodes swell as immune cells multiply inside them. A dental infection is one of the most common reasons people notice a tender lump under the jaw. The swelling usually goes away once the underlying infection clears.
How to Tell Which Gland Is Swollen
Salivary gland problems and lymph node swelling feel different, and the timing of your symptoms is the biggest clue.
A blocked or inflamed salivary gland has a distinctive pattern tied to eating. The swelling and pain get worse during meals, especially if you eat something sour or acidic like a pickle or lemon juice. That’s because your brain signals the gland to produce saliva, but if the duct is blocked, the saliva has nowhere to go and the gland balloons with pressure. The swelling typically peaks for a few minutes during or after a meal, then gradually subsides, only to return the next time you eat. This cycle is sometimes called “mealtime syndrome,” and it’s a strong indicator that the issue is in the salivary gland rather than the lymph nodes.
Swollen lymph nodes, by contrast, tend to stay consistently enlarged and tender regardless of meals. They’re often accompanied by other signs of infection: sore throat, fever, a bad tooth, or a skin wound on the face. The nodes feel like firm, round, mobile lumps that are sore to the touch.
Salivary Stones
The most common reason a submandibular gland swells is a salivary stone, a small calcified deposit that forms inside the gland or its duct and blocks saliva flow. About 84 to 85 percent of all salivary stones occur in the submandibular glands, making this location far more prone to stones than any other salivary gland. The submandibular duct runs upward against gravity and carries thicker, more calcium-rich saliva, both of which make mineral deposits more likely to form.
Stones are thought to develop when tiny mineral deposits inside the gland, or bits of bacteria and food debris that drift into the duct opening, act as a seed. Over time, more calcium layers onto that seed until it’s large enough to partially or fully block the duct. Smoking may also increase the risk. Small stones sometimes pass on their own, especially with hydration and gentle massage of the gland. Larger ones may need to be removed.
The hallmark symptom is one-sided swelling and sharp pain under the jaw that comes on suddenly with eating and eases between meals. If the blockage persists, the gland can become infected, adding redness, warmth, and sometimes a foul-tasting discharge into the mouth from the duct opening under the tongue.
Salivary Gland Infections
When a salivary gland becomes infected, the condition is called sialadenitis. It most commonly affects men between 50 and 70 and causes swelling, tenderness, and sometimes pus draining from the duct. Staphylococcus aureus is the most frequent bacterial culprit, though streptococcus and other bacteria can also be responsible. Infections often develop after a stone blocks the duct, creating a stagnant environment where bacteria thrive, but they can also occur when saliva production drops due to dehydration, certain medications, or medical conditions that cause dry mouth.
Viral infections can also affect salivary glands. Mumps is the classic example, though it primarily targets the parotid glands near the ears rather than the submandibular glands. Other viruses, including HIV, hepatitis C, and influenza, can occasionally involve the salivary glands as well.
Tumors and Growths
Less commonly, a lump under the jaw can be a tumor in the salivary gland itself. Both benign and cancerous tumors tend to show up as painless lumps that grow over time, which is what makes them tricky. A noncancerous growth usually enlarges slowly and stays painless. A cancerous tumor may grow quickly and can cause numbness, weakness, or loss of movement on the affected side of the face. Any persistent, painless lump under the jaw that doesn’t fluctuate with meals or infections deserves evaluation.
It’s also possible for a swollen lymph node under the jaw to signal something more serious than a routine infection. Lymph nodes in this area can enlarge due to cancers of the mouth, skin of the face, or other nearby structures. A node that is hard, fixed in place (doesn’t move when you press on it), keeps growing over several weeks, or is accompanied by unexplained weight loss warrants prompt attention.
What Normal Feels Like
Many people first notice these glands when they’re looking for them, perhaps pressing under their jaw out of curiosity or concern. It’s normal to feel a soft, slightly mobile structure on each side. The submandibular glands themselves are supposed to be there, and healthy lymph nodes are often palpable too, especially in thinner individuals. What matters is change: a gland that suddenly swells, hurts, or feels harder than its counterpart on the other side is giving you information worth paying attention to.