Symptom
Swollen Lymph Nodes: When It's a Cold, When It's Something More
You felt a lump in your neck, armpit, or groin and want to know if it's serious.
Educational, not diagnostic. This page won't tell you whether you have cancer. It will help you have a more productive conversation with your physician. For emergencies, call 911.
Lymph nodes are small filters scattered throughout your body. They swell when they're fighting something — most often a viral or bacterial infection nearby.
A reactive node is usually under 1 cm, tender, mobile under the skin, and shrinks within 2–4 weeks. Concerning nodes are typically larger than 1.5 cm, firm or rubbery, painless, fixed in place, and persist or grow over weeks.
If a node has been present for more than 4 weeks, is growing, or comes with weight loss, night sweats, or fevers, ask for an evaluation. This usually starts with a physical exam and may include an ultrasound or a fine-needle aspiration biopsy.
Common causes — most are not cancer
Recent viral infection
Colds, flu, mononucleosis, COVID — all swell nearby nodes for a few weeks.
Skin or dental infection
A scalp, ear, or tooth infection commonly inflames neck nodes.
Reactive immune response
Vaccinations, allergies, and minor skin breaks can all cause temporary swelling.
Autoimmune conditions
Lupus and rheumatoid arthritis can produce persistent low-grade node enlargement.
Lymphoma or leukemia
A real but less common cause — typically painless, firm, and progressive.
Metastatic cancer
Cancers of the breast, lung, head and neck, or skin can spread to regional nodes.
- A node that's grown over 2–4 weeks instead of shrinking
- Any node larger than 1.5 cm without an obvious infection
- A hard, painless, fixed lump above the collarbone — this is always evaluated
- Generalized swelling in multiple regions at once
- Night sweats, unexplained weight loss, or persistent fever
- Itching all over the body without a rash
What a proper work-up looks like
- 1
Exam of all node regions
Neck, armpits, groin, and the area drained by the swollen node.
- 2
Targeted labs
CBC with differential, LDH, and screening for infections (EBV, HIV, tuberculosis) when indicated.
- 3
Imaging
Ultrasound for superficial nodes; CT or PET for deeper or generalized swelling.
- 4
Biopsy if warranted
A core or excisional biopsy is the only definitive way to distinguish reactive nodes from lymphoma.
Questions worth bringing to your appointment
- Does the location and feel of this node concern you?
- Should we watch it for a few weeks or biopsy it now?
- What would a biopsy involve and how soon could I get one?
- Which type of specialist do I need — ENT, hematology, or surgical oncology?
Frequently asked questions
How big does a lymph node have to be before it's worrying?
Generally, nodes larger than 1.5 cm in adults that persist beyond 4 weeks without explanation warrant evaluation. Supraclavicular (above the collarbone) nodes of any size are always evaluated.
Are painful lymph nodes less likely to be cancer?
Usually yes. Painful, tender nodes are more often infectious. Painless, firm, slowly growing nodes are more concerning. But this rule isn't absolute — when in doubt, get it checked.
What kind of biopsy do they do on a lymph node?
An ultrasound-guided core needle biopsy is common. For suspected lymphoma, surgeons often prefer an excisional biopsy — removing the whole node — because architecture matters for accurate diagnosis.
Insurance accepted
Coverage details vary by plan. Our care coordinators help verify your benefits before scheduling.
Want a calm, expert opinion on what's going on?
Request a new patient consultation or independent second opinion with Keck Medicine of USC — Newport Beach. Most major insurance accepted.
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