Common

Swollen Lymph Nodes: Causes & Assessment

Swollen lymph nodes are usually a sign your immune system is fighting an infection — but persistent, hard, or widespread swelling deserves proper assessment.

Most common cause
Viral infection (usually resolves in 2-3 weeks)
Concerning if
>2-3cm, hard, fixed, or persisting >4-6 weeks
Common sites
Neck, armpit, groin
Key test if concerning
FBC + biopsy if persistent

Common Benign Causes

Red Flags Suggesting Further Investigation

FeatureConcern Level
Size >2-3cmHigher concern
Hard, rubbery, or fixed (doesn't move under skin)Higher concern — possible lymphoma or metastatic cancer
Persisting beyond 4-6 weeks without explanationWarrants investigation
Associated with night sweats, weight loss, feverSuggests lymphoma — needs urgent assessment
Multiple sites, especially above and below the diaphragmMore concerning pattern
Soft, tender, mobile, recent infectionUsually benign — reactive to infection

Investigation If Concerning

TestPurpose
FBC with differentialInfection pattern vs abnormal cells (leukaemia)
ESR/CRPInflammation marker
LDHElevated in lymphoma
Monospot/EBV serologyGlandular fever
Ultrasound/biopsyDefinitive assessment of persistent nodes
See a Doctor Urgently IfLymph node swelling is hard, non-tender, rapidly growing, or accompanied by unexplained weight loss, drenching night sweats, or persistent fever — these features warrant prompt assessment to exclude lymphoma or other serious causes.
Location Gives CluesNeck nodes often relate to throat/dental infections; armpit nodes to arm/hand infections or (rarely) breast issues; groin nodes to leg/foot infections or (rarely) pelvic conditions. Persistent nodes in unusual locations deserve more thorough assessment.
How long should swollen lymph nodes take to go down?
Most infection-related swelling resolves within 2-3 weeks as the infection clears. Persisting beyond 4-6 weeks without an obvious ongoing cause warrants medical assessment.
Are swollen lymph nodes always a sign of cancer?
No — the vast majority of swollen lymph nodes are due to common infections and resolve on their own. Cancer-related lymph node swelling has specific concerning features (hard, fixed, persistent, systemic symptoms) as outlined above.
Can stress cause swollen lymph nodes?
Not directly, but stress can make you more susceptible to infections (through immune suppression), which can then cause reactive lymph node swelling.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.