A swollen lymph node is usually not bad. The most common cause is an infection, typically something as routine as a cold, and the swelling goes down on its own once the infection clears. Cancer rarely causes swollen lymph nodes. That said, certain characteristics of the swelling, where it is on your body, and how long it lasts can separate a harmless node from one worth investigating.
Why Lymph Nodes Swell in the First Place
Lymph nodes are small, bean-shaped filters scattered throughout your body. They trap bacteria, viruses, and other foreign material so your immune cells can destroy them. When your body is fighting something off, the nodes nearest to the problem fill with extra immune cells and fluid, which makes them swell. This is your immune system working correctly, not a sign that something has gone wrong.
The most common triggers are everyday infections: colds, strep throat, ear infections, infected teeth, skin infections like cellulitis, and mononucleosis. Less common infectious causes include tuberculosis, syphilis, toxoplasmosis (a parasitic infection), and cat scratch fever. Autoimmune conditions like lupus, rheumatoid arthritis, and sarcoidosis can also cause persistent node swelling because the immune system stays chronically activated.
Cancer does cause swollen lymph nodes in some cases, either from cancers that start in the lymph system (lymphoma, leukemia) or from other cancers that have spread. But this is the exception. In a study of 500 children with swollen lymph nodes, 87.4% turned out to be simple reactive swelling, 6.8% were infectious, and only about 5.8% were cancerous. While the exact percentages shift in older adults, infection remains the leading cause across all age groups.
What a Normal Swollen Node Feels Like
A swollen lymph node from an infection is typically tender or painful to the touch, soft or slightly squishy, and moves freely under your skin when you press on it. It often appears near an obvious source of infection. A sore throat, for instance, commonly produces swollen nodes along the sides of your neck. An infected cut on your hand might cause a node to pop up in your armpit. These nodes are usually pea-sized to grape-sized.
You can check your own lymph nodes using your fingertips in a gentle, circular motion. Feel both sides of your body for comparison. The most accessible nodes are along your jawline, the sides and back of your neck, behind your ears, in your armpits, and in your groin. Finding a small, tender, movable node during a cold or after a minor infection is perfectly normal.
Signs That Deserve Attention
Certain features make a swollen lymph node more concerning. The node itself may feel firm or rubbery rather than soft, stay fixed in place rather than sliding under your skin, or be completely painless. Painless swelling is actually the most common sign of lymphoma. Nodes that keep growing over several weeks instead of shrinking also warrant a closer look.
Location matters significantly. Swollen nodes in the neck, armpit, or groin are extremely common and usually benign. But a swollen node just above the collarbone (the supraclavicular area) carries a much higher risk. In people over 40, supraclavicular swelling is associated with malignancy roughly 90% of the time. In people under 40, that number drops to about 25%, but it’s still high enough that any new lump in this area should be evaluated promptly. Right-sided supraclavicular nodes can signal problems in the chest or lungs, while left-sided ones can reflect issues in the abdomen, including the stomach, kidneys, or reproductive organs.
Pay attention to symptoms happening alongside the swelling. Three specific warning signs, sometimes called “B symptoms,” are strongly linked to lymphoma:
- Unexplained fevers above 100.4°F (38°C)
- Drenching night sweats severe enough that you need to change your bedclothes
- Unexplained weight loss of more than 10% of your body weight over six months
Any combination of these symptoms alongside persistent node swelling is worth bringing to a doctor quickly.
How Long Is Too Long
Most infection-related swelling peaks within a few days and resolves within one to two weeks as the infection clears. The British Association of Dermatologists recommends contacting your doctor if a swollen node hasn’t reduced in size within a week. That doesn’t mean a node still present at day eight is dangerous. It means it’s reasonable to get it checked rather than continuing to wait.
Nodes that persist beyond two to four weeks without an obvious cause, or that continue to grow, generally get a more thorough evaluation. Your age plays into how aggressively this is pursued. Persistent swelling in a child is far more likely to be reactive than malignant. In adults over 40, especially with supraclavicular involvement or the warning symptoms listed above, the threshold for further testing is lower.
What Happens if Your Doctor Investigates
Evaluation usually starts with a physical exam and questions about recent infections, travel, pet exposure, and other symptoms. Blood work can reveal signs of infection or blood cancers. Imaging, typically an ultrasound, helps measure the node and assess its internal structure.
If a biopsy is needed, the type depends on the situation. A fine-needle aspiration uses a thin needle to collect fluid and cells from the node through your skin. A core needle biopsy uses a slightly larger needle to get an intact tissue sample. Both are relatively quick outpatient procedures. For suspected lymphoma, doctors sometimes prefer to remove the entire node (excisional biopsy) because the architecture of the tissue matters for an accurate diagnosis.
Monitoring at Home
If you’ve found a swollen node and aren’t sure whether to worry, keep track of it. Check it once a month using your fingertips, noting whether it’s getting bigger, staying the same, or shrinking. Compare both sides of your body, since asymmetry can be informative. A warm compress and over-the-counter pain relievers can help with discomfort from infection-related swelling.
The key things to watch for: a node that grows steadily over weeks, becomes hard or fixed, appears above the collarbone, or shows up alongside fevers, night sweats, or unexplained weight loss. If none of those apply and you’re dealing with a tender, movable node during or after an obvious infection, the odds are heavily in your favor that it will resolve on its own.