Several sexually transmitted infections can cause groin pain, either through swollen lymph nodes, nerve irritation, or inflammation spreading to nearby structures. The most common culprits are genital herpes, chlamydia (including its aggressive variant LGV), gonorrhea, syphilis, and chancroid. The type of pain and how quickly it appears after exposure varies significantly between infections, which can help narrow down the cause.
Genital Herpes
Genital herpes is one of the most common STIs to cause noticeable groin pain. During a first outbreak, the lymph nodes in the groin typically swell and become tender on both sides. This swelling accompanies the more recognizable symptoms: painful blisters or sores on the genitals, buttocks, or inner thighs, along with flu-like symptoms including fever, headache, and muscle aches. Symptoms tend to appear within about 12 days of exposure.
Herpes also causes a distinctive pattern of nerve-related pain that other STIs don’t typically produce. Before an outbreak recurs, many people experience warning signs called prodromal symptoms: tingling, shooting pain in the legs, hips, or buttocks, and general genital discomfort. This happens because the herpes virus lives in nerve cells and travels along nerve pathways when it reactivates. So if your groin pain has a tingling or shooting quality and comes and goes in episodes, herpes is a strong possibility.
Chlamydia and Gonorrhea
Chlamydia and gonorrhea don’t usually cause groin pain directly, but they can when the infection spreads deeper into the reproductive tract. In men, both infections are the leading cause of epididymitis, an inflammation of the coiled tube at the back of the testicle. Epididymitis causes pain or discomfort in the lower abdomen, pelvic area, and testicles. If it spreads to the testicle itself, the condition becomes more serious. Chlamydia symptoms, when they appear at all, typically start 5 to 14 days after exposure and can include testicle pain or swelling.
In women, untreated chlamydia or gonorrhea can lead to pelvic inflammatory disease, which causes lower abdominal and pelvic pain that can radiate into the groin. Because both infections are frequently silent (especially chlamydia, which often produces no symptoms at all), groin or pelvic pain may be the first sign that something is wrong.
Lymphogranuloma Venereum (LGV)
LGV is caused by specific, more aggressive strains of the same bacteria behind chlamydia. It deserves its own category because the groin pain it produces is dramatically different from ordinary chlamydia. LGV causes large, painful swellings in the groin called buboes, which are clusters of inflamed lymph nodes that can grow to a significant size, fill with pus, and sometimes rupture through the skin, creating draining tracts.
The infection starts with a small blister at the site of contact that often goes unnoticed and heals quickly on its own. Weeks later, the lymph nodes in the groin swell and become intensely tender. In men, this swelling typically affects one or both sides of the groin. In women, the lymph nodes near the rectum and pelvis are more commonly involved, causing back pain and deep pelvic pain rather than the visible groin swelling seen in men. LGV is most frequently reported among men who have sex with men, particularly those living with HIV.
Syphilis
Syphilis causes groin lymph node swelling, but with one important distinction: it’s usually painless. During the first stage, a small, painless sore called a chancre forms where the bacteria entered the body. The lymph nodes in the groin swell on both sides but typically don’t hurt and don’t produce pus. This painless quality sets syphilis apart from nearly every other STI that affects the groin.
If you have swollen groin lymph nodes without tenderness or pain, syphilis is a possibility worth testing for. As the infection progresses to the second stage, lymph node swelling can become more widespread, appearing in other parts of the body alongside a rash, fever, and fatigue.
Chancroid
Chancroid is less common in developed countries but still occurs and causes some of the most painful groin symptoms of any STI. It produces soft, painful genital ulcers (unlike the painless sores of syphilis) along with tender, swollen inguinal lymph nodes that can suppurate, meaning they fill with pus and may burst. The combination of a painful genital sore and a painful groin lump is a hallmark pattern of chancroid.
How Timing Helps Identify the Cause
The gap between sexual exposure and the onset of groin pain can help point toward a specific infection. Herpes symptoms tend to appear within about 12 days. Chlamydia symptoms, if they show up, typically start within 5 to 14 days, though complications like epididymitis may take longer to develop. Syphilis has a more variable timeline, with the initial chancre sometimes appearing weeks after exposure and lymph node swelling following shortly after. LGV has a longer arc: the initial blister appears and heals within days, but the painful groin swelling doesn’t develop until weeks later during the second stage of infection.
Painful vs. Painless Swelling
One of the most useful ways to narrow down the cause is whether the groin swelling hurts. Herpes, LGV, and chancroid all produce tender, painful lymph nodes. Syphilis, by contrast, causes painless swelling that doesn’t suppurate. This distinction alone can guide a clinician toward the right tests. Herpes-related lymph node tenderness is typically bilateral (both sides), matching the pattern of genital lesions. LGV buboes in men often affect one side more than the other, and the swelling can become dramatic enough that the skin overlying the nodes breaks down.
Getting Tested
Groin pain with any recent sexual exposure warrants STI testing, even if no visible sores are present. Many of these infections overlap in symptoms, and some (particularly chlamydia and early syphilis) can be nearly silent. Standard STI panels cover chlamydia, gonorrhea, syphilis, and HIV. Herpes testing usually requires either a swab of an active sore or a type-specific blood test. LGV requires specialized testing that isn’t always included in routine screens, so mention groin swelling specifically when you’re evaluated.
All of these infections are treatable. Bacterial infections like chlamydia, gonorrhea, syphilis, LGV, and chancroid are cured with antibiotics, often in a single course lasting one to two weeks. Herpes is managed with antiviral medication that shortens outbreaks and reduces their frequency, though the virus remains in the body long-term. Early treatment prevents complications and reduces the chance of passing the infection to others.