What causes swollen lymph nodes?

Lymph nodes filter lymph fluid and help coordinate immune responses. A nearby infection, such as a throat, dental, skin, or respiratory infection, can make nodes tender and enlarged. Inflammatory illnesses can do the same. Cancer can also involve lymph nodes: lymphoma begins in lymphatic cells, while metastatic cancer reaches nodes from another body site. A swollen node is therefore a sign of immune or tissue activity, not a diagnosis by itself.

The location, texture, number of nodes, tenderness, and the time course help clinicians decide what to investigate. Nodes near an infection often change as that illness improves, while persistent, firm, fixed, or steadily enlarging nodes need examination.

Note where the swelling is, when it began, whether it is painful, and whether you have fever, night sweats, weight loss, rash, cough, or a recent infection. Arrange an appointment for a node that remains enlarged, grows, feels hard or fixed, or has no obvious explanation. A clinician may examine nearby areas and choose observation, blood tests, imaging, or a sample based on the findings.

Seek urgent help for swollen nodes with trouble breathing or swallowing, rapidly spreading neck swelling, severe weakness, or a high fever with confusion. Arrange prompt medical review for persistent painless enlargement, drenching night sweats, unexplained weight loss, repeated fevers, or nodes above the collarbone. These features can have non-cancer causes, but they warrant timely assessment.

Ask which nearby infection or inflammation could explain the node, how long it is reasonable to observe, and what change should bring you back sooner. If testing is recommended, ask what an ultrasound, scan, or biopsy would clarify and how results guide the next step.