Why Do I Have A Lump Under My Jaw? Root Causes

A lump under your jaw is usually a swollen lymph node or an enlarged salivary gland, and in most cases it reflects your body reacting to a nearby infection rather than a sign of cancer. Lymph nodes in this area filter fluid from the mouth, throat, and face, so they often swell when you have a cold, a sore throat, an ear infection, or a dental problem. Salivary gland swelling can produce a similar lump just below the jawline. Less often, the cause is a cyst, a benign growth, or a more serious condition that needs medical evaluation.

Why Do I Have A Lump Under My Jaw?

Your neck and jaw area contains a dense network of lymph nodes. These small, bean-shaped structures are part of the immune system. They trap bacteria, viruses, and other foreign particles that travel through lymph fluid.

When your body fights an infection, immune cells inside the lymph nodes multiply. The node swells as a result. This is called reactive lymphadenopathy, and it is the single most common reason for a lump under the jaw.

There are two other structures in this region that can produce a lump:

• Salivary glands — the submandibular glands sit directly under the jawbone. They can swell from infection, blockage, or other causes.
• Other tissues — cysts, fatty growths (lipomas), and rarely tumors can develop in the soft tissue of the neck.

Most lumps under the jaw are harmless and shrink once the underlying infection clears. The challenge is knowing when a lump is just a reactive lymph node and when it signals something that needs prompt attention.

What Infections Cause a Lump Under the Jaw?

Infections are by far the most common trigger. The lymph nodes under the jaw drain the mouth, throat, tonsils, and skin of the face. Any infection in those areas can cause them to swell.

Common infectious causes include:

• Upper respiratory infections — colds, flu, and similar viral illnesses frequently cause tender, swollen nodes under the jaw.
• Strep throat and tonsillitis — bacterial throat infections often produce enlarged, painful lymph nodes in the neck.
• Ear infections — infections in the middle ear can drain to nearby lymph nodes.
• Dental infections — abscessed teeth, gum disease, and impacted wisdom teeth are frequent culprits. A dental infection on one side often causes a lump on that same side.
• Mononucleosis — this viral infection commonly causes widespread lymph node swelling, including under the jaw.
• Skin infections — infected cuts, boils, or acne on the face or scalp can trigger node swelling.
• Cat scratch disease — a bacterial infection from a cat scratch or bite can cause a swollen node near the jaw or neck.
• Tuberculosis — in some cases, TB can affect lymph nodes in the neck, though this is less common in the United States.

With an infection, the lump is often tender, movable, and accompanied by other symptoms like fever, sore throat, or ear pain. It typically shrinks within a few days to a few weeks as the infection resolves.

Can Salivary Gland Problems Cause a Lump Under the Jaw?

Yes. The submandibular salivary glands sit just inside the jawbone on each side. When these glands swell, they create a lump that can feel like it is under the jaw itself.

Salivary gland swelling has several possible causes:

• Salivary stones — calcium deposits can block the duct that drains the gland. This causes pain and swelling, especially when eating or drinking. The gland may swell up right before a meal and then shrink afterward.
• Sialadenitis — this is an infection of the salivary gland itself, often bacterial. It causes pain, redness, and swelling over the gland.
• Viral infections — mumps classically causes salivary gland swelling, though vaccination has made it rare in the US. Other viruses can also inflame the glands.
• Autoimmune conditions — Sjögren’s disease and similar conditions can cause chronic salivary gland enlargement.
• Tumors — most salivary gland tumors are benign, but some are malignant. These typically present as a slow-growing, painless lump.

Salivary gland lumps tend to be located slightly higher and more forward than lymph node lumps. They may worsen with eating. A blocked duct often causes intermittent swelling that comes and goes with meals.

When Is a Lump Under the Jaw a Sign of Something Serious?

Most lumps under the jaw are not cancer. But certain features raise concern and warrant prompt medical evaluation.

See a doctor if the lump has any of these characteristics:

• Persists for more than two to three weeks without shrinking
• Is hard or fixed — feels firm and does not move when you push on it
• Grows steadily over days or weeks
• Is painless — cancerous nodes are often painless, while infected ones tend to hurt
• Is accompanied by other symptoms — unexplained weight loss, night sweats, persistent fever, difficulty swallowing, hoarseness, or a sore in the mouth that will not heal
• Appears alongside a known cancer risk — tobacco use, heavy alcohol use, or a previous cancer diagnosis

Cancers that can cause a lump under the jaw include lymphomas, oral cancers, throat cancers, and salivary gland cancers. These are much less common than infections, but they need to be ruled out when a lump does not behave like a reactive lymph node.

A key point: a lump that is tender and comes and goes with a sore throat is almost always benign. A lump that is painless, firm, and steadily growing is the pattern that deserves a closer look.

How Are Lumps Under the Jaw Evaluated?

Doctors assess a neck lump through history, physical exam, and sometimes imaging or biopsy.

The physical exam focuses on:

• Size, shape, and consistency of the lump
• Whether it is tender or painless
• Whether it moves freely or is fixed to surrounding tissue
• Whether other lymph nodes are enlarged
• Whether there are signs of infection in the mouth, throat, or ears

If the cause is not obvious from the exam, further testing may include:

• Blood tests — to check for infection, inflammation, or blood disorders
• Ultrasound — often the first imaging choice for neck lumps; it can show whether a node has normal or suspicious features
• CT or MRI — used when deeper structures need to be evaluated
• Fine-needle aspiration — a thin needle removes cells from the lump for lab analysis; this is often used when cancer is a concern
• Excisional biopsy — surgical removal of the lump for full examination, sometimes needed when needle results are unclear

If a dental infection is suspected, a dental exam and X-rays may be part of the workup. Treating the dental problem often resolves the lump.

What Does Treatment Look Like?

Treatment depends entirely on the cause. There is no single approach for a lump under the jaw.

• Bacterial infections — antibiotics are used when a bacterial cause is identified or strongly suspected. Viral infections do not respond to antibiotics.
• Dental infections — treatment may involve antibiotics, drainage of an abscess, root canal, or tooth extraction.
• Salivary stones — small stones may pass on their own with hydration and sour candy to stimulate saliva flow. Larger stones may need removal by a specialist.
• Sialadenitis — bacterial sialadenitis is treated with antibiotics, hydration, and sometimes massage of the gland.
• Autoimmune conditions — managed with medications that reduce immune system activity, depending on the specific disease.
• Cancer — treatment depends on the type and stage. Options may include surgery, radiation, chemotherapy, or a combination.

For a reactive lymph node from a minor infection, no specific treatment is needed beyond treating the underlying illness. Warm compresses and over-the-counter pain relievers may ease discomfort. The node typically returns to normal size within a few weeks.

Can You Prevent a Lump Under the Jaw?

You cannot prevent every cause, but you can reduce the risk of some.

• Practice good dental care — brush twice daily, floss, and see a dentist regularly. This lowers the risk of dental infections that cause lymph node swelling.
• Treat throat and ear infections promptly — see a doctor if symptoms persist or worsen.
• Stay up to date on vaccinations — the mumps vaccine, for example, prevents a common cause of salivary gland swelling.
• Avoid tobacco and limit alcohol — both increase the risk of head and neck cancers.
• Drink enough water — hydration helps prevent salivary stones.

These steps lower risk but do not eliminate it. Many causes of neck lumps are not preventable.

What Else Can Cause a Lump Under the Jaw?

Beyond infection and salivary gland issues, several other conditions can produce a lump in this area.

• Epidermoid cysts — small, benign sacs under the skin that can appear anywhere, including the jawline. They are usually painless and movable.
• Lipomas — benign fatty tumors that feel soft and doughy. They grow slowly and are not cancerous.
• Thyroglossal duct cysts — a remnant of thyroid development that forms a cyst in the midline of the neck. These are usually present from childhood but can appear later.
• Branchial cleft cysts — another congenital remnant, typically found on the side of the neck.
• Lymphoma — cancer of the lymphatic system can cause painless lymph node swelling in the neck and elsewhere.
• Metastatic cancer — cancer that has spread from another site, such as the mouth, throat, or thyroid, can appear as a neck lump.

These causes are less common than infection, but they are part of the differential diagnosis. A doctor can usually narrow down the possibilities with a physical exam and basic testing.