A handful of sexually transmitted infections can cause joint pain or swelling. The most important are gonorrhea (which can spread to the joints and cause disseminated gonococcal infection), chlamydia (a classic trigger of reactive arthritis), and hepatitis B (whose early phase can include achy joints). But injury and ordinary arthritis cause joint pain far more often, and a test is what settles which it is.
Neisseria gonorrhoeae
Chlamydia trachomatis
Hepatitis B virus
| Item | Value |
|---|---|
| Gonorrhea | curable — Neisseria gonorrhoeae |
| Chlamydia | curable — Chlamydia trachomatis |
| Hepatitis B | managed — Hepatitis B virus |
Which STIs can cause joint pain or reactive arthritis?
Two mechanisms are at work. In the first, the bacteria themselves travel to a joint and inflame it directly. In the second, called reactive arthritis, the infection lives in the genitals or gut while the immune system overreacts and attacks the joints, tendons, and sometimes the eyes and skin days to weeks later. Each candidate below has a different tell-tale pattern.
Gonorrhea
Gonorrhea is caused by the bacterium Neisseria gonorrhoeae, which can infect the genitals, rectum, and throat CDC. Most genital cases announce themselves locally: men often get burning on urination and a white, yellow, or green penile discharge, and less commonly swollen, painful testicles; women frequently have no symptoms, or notice painful urination, more vaginal discharge, or bleeding between periods. The joint connection comes when an untreated infection spreads through the bloodstream — disseminated gonococcal infection (DGI). That looks like fever, scattered skin sores, painful tendons (tenosynovitis), and a hot, swollen joint or migrating joint pains. With DGI the germ is actually inside the joint, so prompt treatment is urgent. Learn more about gonorrhea.
Chlamydia
Chlamydia is caused by the bacterium Chlamydia trachomatis, and most US genital infections come from serovars D–K CDC. It's a famously silent infection: roughly three-quarters of infected women and about half of infected men feel nothing at all. When symptoms do show, they usually appear within one to three weeks of exposure: abnormal discharge, burning on urination, and, if it spreads upward, lower abdominal or low-back pain. Chlamydia is the most common trigger of reactive arthritis in the US. Here the joint itself isn't infected. The immune system, primed by the genital infection, inflames the knees, ankles, or feet, sometimes alongside eye redness and urinary symptoms. It tends to be asymmetric, affecting one knee rather than both, and follows the original infection by days to weeks. Read more about chlamydia.
Hepatitis B
Hepatitis B is a vaccine-preventable liver infection caused by the hepatitis B virus (HBV), spread mainly through blood and sex CDC. Many people have no symptoms. When acute illness does occur, it tends to arrive on average about 90 days after exposure (range roughly 60 to 150 days) and can include joint pain along with fatigue, fever, poor appetite, nausea, abdominal pain, dark urine, clay-colored stools, and jaundice (a yellowing of the skin and eyes from a struggling liver). The achy joints of early hepatitis B are an immune-complex reaction, with circulating virus particles and antibodies depositing in the joints, and they usually come bundled with those other liver clues rather than alone. Joint pain plus dark urine or yellowing points away from a simple STI joint problem; review the full list of hepatitis b symptoms.
When joint pain is NOT an STI
Most joint pain has nothing to do with an infection. An STI is a relatively uncommon cause, and the everyday explanations are far more likely. Before you assume the worst, consider:
- Injury or overuse — a twisted ankle, a strained knee, or repetitive strain, which usually traces back to a specific activity.
- The common forms of arthritis — osteoarthritis (wear-and-tear cartilage breakdown) and the inflammatory autoimmune types, which tend to be chronic and often symmetric.
- Other infections and viral illnesses that cause transient achy joints unrelated to anything sexually transmitted.
These causes overlap too much to tell apart by sight, and several STIs are frequently silent. Symptoms point you toward testing; they don't replace it.
How to tell them apart
Clinicians lean on the pattern, the timing, and the company the joint pain keeps:
- Pattern: a single hot, swollen joint with fever and skin sores suggests disseminated gonorrhea; an asymmetric flare in the knees, ankles, or feet after a genital infection suggests reactive arthritis; symmetric, long-running stiffness leans toward ordinary inflammatory arthritis.
- Timing: reactive arthritis tends to follow a chlamydia infection by days to weeks; hepatitis B joint pain shows up roughly three months after exposure with liver symptoms.
- Company it keeps: burning urination or discharge points to gonorrhea or chlamydia; jaundice and dark urine point to hepatitis B; a recent sprain points to injury.
None of this is reliable enough to bet on. The discriminating features narrow the list, but a test is what turns a guess into an answer.
Side-by-side comparison
| Cause | Joint mechanism | Tell-tale pattern | Typical timing | Other clues |
|---|---|---|---|---|
| Gonorrhea (DGI) | Bacteria spread into the joint | One hot, swollen joint or migrating pain; tendon pain | After untreated infection | Fever, skin sores, genital discharge |
| Chlamydia (reactive arthritis) | Immune reaction, joint not infected | Asymmetric knees/ankles/feet | Days to weeks after genital infection | Eye redness, urinary symptoms, often silent infection |
| Hepatitis B | Immune-complex deposition | Achy joints with the acute illness | ~90 days after exposure (range 60–150) | Jaundice, dark urine, fatigue, nausea |
| Non-STI (injury/arthritis) | Mechanical or autoimmune | Activity-linked or symmetric, chronic | Varies | No genital or liver symptoms |
How it's tested
For gonorrhea and chlamydia, a nucleic acid amplification test (NAAT) is the recommended method, with gonorrhea NAATs running high sensitivity (usually over 90%) and specificity around 99% CDC STI Treatment Guidelines, 2021. Hepatitis B is diagnosed with a triple serologic panel — HBsAg for active infection, anti-HBs for immunity or recovery, and total anti-HBc for past or current infection — and CDC recommends every adult be screened at least once in their lifetime CDC, 2023. In practice that means a urine sample, a self-collected swab, a blood draw, or a quick exam depending on what's suspected, with results usually back in a few days. See the full workup on the get tested page, and check when to test after exposure so you don't test too early to catch it.
What to do next
If a test confirms an STI, treatment is straightforward and effective: gonorrhea is treated with an injection, chlamydia with a short course of antibiotics, and the joint symptoms typically settle once the underlying infection is cleared. Hepatitis B is managed differently and may need specialist follow-up. Don't wait out joint pain hoping it passes, because untreated gonorrhea that has already reached a joint can damage it. Get tested, get the result, and start treatment for what's actually there. Testing is free or low-cost at health departments, Planned Parenthood, and Title X clinics.
Red flags — when to get seen urgently
Some joint symptoms shouldn't wait for a routine appointment. Seek care quickly if you have:
- A single joint that is hot, red, severely swollen, and intensely painful — especially with fever, which can signal a joint infection that needs urgent drainage and antibiotics.
- Joint pain combined with fever and scattered skin sores, the picture of disseminated gonorrhea.
- Joint pain alongside yellowing skin or eyes, dark urine, or severe abdominal pain, which points to the liver.
- Eye redness or pain with joint swelling, which can accompany reactive arthritis and needs prompt evaluation to protect vision.
- Inability to bear weight or move the joint at all.