Which STDs Cause Swollen Lymph Nodes? Groin & Neck

Why STDs swell your lymph nodes

Lymph nodes are filtration stations — when pathogens drain from infected tissue into nearby nodes, immune cells multiply rapidly to fight back, physically enlarging the gland. That's why node location maps onto infection location:

Tenderness suggests active battle; firm, painless, rubbery nodes can also be significant — syphilis nodes classically don't hurt.

LGV: the lymph-node specialist

Lymphogranuloma venereum deserves special mention — it's literally named for this symptom. Caused by invasive L-strains of chlamydia trachomatis, LGV begins with a small painless genital lesion, then progresses weeks later to painful, matted groin node clusters called buboes, sometimes rupturing through skin. Once rare in Western countries, LGV circulates among men who have sex with men, particularly with receptive anal exposure where it causes severe proctitis.

Standard chlamydia tests detect the organism but not the strain; diagnosis needs specialized PCR typing. Suspicion pattern = rectal pain + tenesmus + groin nodes → request LGV evaluation specifically.

When swollen nodes mean get tested

• Groin nodes + any genital sore/bump — even painless ones.
• Widespread swelling + fever + recent new partner — HIV RNA test, not just antibody.
• Any node enlarged beyond 2–3 weeks without shrinking.
• Nodes with night sweats or unexplained weight loss — broaden evaluation beyond STIs promptly.

Panels covering HIV, syphilis, herpes and chlamydia address every infectious node-suspect in one visit. Start at where to get tested; timing per pathogen in the window chart.