A swollen lymph node usually means your immune system is fighting an infection nearby. Lymph nodes are small, bean-shaped filters scattered throughout your body, and they swell when they trap bacteria, viruses, or other threats and ramp up the production of immune cells. In the vast majority of cases, the swelling is temporary and harmless. But in some situations, a swollen node can signal something more serious, from an autoimmune condition to cancer.
Why Lymph Nodes Swell
Lymph nodes act like checkpoints for your immune system. Fluid from nearby tissues drains through them, and if that fluid carries anything suspicious, the node activates. White blood cells multiply inside it, the node fills with inflammatory material, and you feel a lump that may be tender to the touch. This is a normal, healthy response.
The most common trigger is a straightforward infection. A cold, the flu, a sore throat, an ear infection, or a skin wound near the node can all cause noticeable swelling. In children especially, short-lived viral illnesses are the leading cause of swollen nodes in the head and neck. Bacterial skin infections from staph or strep, mononucleosis (caused by the Epstein-Barr virus), and even a cat scratch (from a bacterium called Bartonella) are other frequent culprits.
What the Location Tells You
Your body has roughly 600 lymph nodes, but you can only feel the ones close to the surface. Where a node swells often points directly to where the problem is, because each group of nodes drains a specific region.
- Under the jaw or chin: These nodes drain the mouth, gums, tongue, cheeks, and lips. Swelling here commonly follows a dental infection, cold sore, or upper respiratory infection.
- Sides and back of the neck: Cervical nodes collect fluid from the entire head and neck. A sore throat, ear infection, or sinus infection is the usual cause.
- Behind the ear: These drain the upper ear and back of the scalp. Ear infections and scalp conditions often show up here.
- Armpit: Axillary nodes drain the arms, chest wall, and breast tissue. A cut on your hand, a skin infection on your arm, or even a recent vaccination in that arm can trigger swelling.
- Groin: Inguinal nodes drain the legs, feet, and genital area. Skin infections on the lower body, sexually transmitted infections, or minor injuries to the feet and legs are common triggers.
- Above the collarbone: This location is more concerning. A swollen node in the left supraclavicular area, sometimes called Virchow’s node, receives drainage from the abdominal cavity and can indicate cancers of the stomach, kidneys, or ovaries. Swelling here warrants prompt evaluation.
One Area vs. Multiple Areas
When only one group of nodes swells (localized lymphadenopathy), infection near that area is the most likely explanation. This is the pattern you see with a throat infection causing neck swelling or a cut on your leg causing groin swelling.
When nodes swell in two or more separate regions at the same time (generalized lymphadenopathy), the cause is typically something affecting the whole body. Benign causes include viral illnesses like mono and certain medications. More serious possibilities include autoimmune diseases, widespread infections like HIV or tuberculosis, and cancers that have spread through the lymphatic system. Generalized swelling almost always needs medical investigation.
Autoimmune Conditions and Lymph Nodes
Your immune system can also cause lymph node swelling when it misfires against your own tissues. Lupus is one of the more common autoimmune diseases associated with swollen nodes, and it can cause generalized lymphadenopathy alongside joint pain, fatigue, and skin rashes. Rheumatoid arthritis, Sjögren syndrome (which causes dry eyes and mouth), and dermatomyositis can all trigger persistent node swelling as well. In these cases, the swelling tends to come and go alongside disease flares rather than resolving on its own within a few weeks.
How to Tell Normal Swelling From Something Serious
Most swollen lymph nodes are soft, mobile, and tender. They hurt a little when you press on them, they move freely under your skin, and they shrink back to normal within two to four weeks as the infection clears. These are reassuring features.
Certain characteristics are more worrisome. A node that is hard, rubbery, or fixed in place (meaning it doesn’t slide under your fingers) deserves attention. Painless swelling that grows steadily over weeks is another red flag, because cancerous nodes often don’t hurt. Nodes larger than about 1 centimeter in their shortest dimension are generally considered clinically enlarged, though some locations have different thresholds. Size alone isn’t diagnostic, but a node that keeps getting bigger rather than shrinking is more concerning than one that stays the same.
The systemic symptoms that oncologists look for alongside swollen nodes, sometimes called B-symptoms, include unexplained fevers above 100.4°F, drenching night sweats severe enough to require changing your bedclothes, and unexplained weight loss of more than 10% of your body weight over six months. These symptoms in combination with persistent node swelling raise the possibility of lymphoma or another blood cancer and call for prompt evaluation. Other symptoms like itching and fatigue can occur too, though they’re considered less specific on their own.
What Happens During Evaluation
If you visit a doctor about a swollen node, the evaluation usually starts with a physical exam and questions about recent illnesses, travel, animal exposure, medications, and how long the node has been swollen. Blood tests can help identify infections or immune system abnormalities.
If the node doesn’t resolve after two to four weeks and there’s no obvious infection to explain it, imaging with ultrasound or a CT scan is a common next step. The imaging helps characterize the node’s size, shape, and internal structure. If the results are still unclear, a biopsy (removing part or all of the node for microscopic examination) gives the most definitive answer. In many cases, though, the node shrinks on its own before any of this becomes necessary.
What You Can Do at Home
For garden-variety swollen nodes caused by a cold or minor infection, there’s no specific treatment for the node itself. It will resolve as the infection clears. A warm compress over the area and over-the-counter pain relievers can ease discomfort. Staying hydrated and resting helps your body fight off the underlying infection faster.
Keep track of the node’s size and how long it’s been swollen. If it’s still there after four weeks, is getting larger, feels hard or immovable, or you develop fevers, night sweats, or unexplained weight loss, those are the signals that warrant a medical visit rather than continued waiting.