Chlamydia is easily curable with antibiotics, but untreated, it can cause serious and sometimes permanent damage. The infection is one of the most common sexually transmitted infections worldwide, and its biggest danger is how quietly it operates: roughly 60% of women with chlamydia have no symptoms at all, meaning the infection can silently progress for months before anyone catches it.
Why Most People Don’t Know They Have It
Chlamydia earns its reputation as a “silent” infection because the majority of cases produce no noticeable symptoms, especially in women. Men are somewhat more likely to notice something, often burning during urination or discharge, but many men are also asymptomatic. This is the core reason chlamydia becomes serious: people carry it without knowing, giving it time to spread to partners and cause internal damage.
When symptoms do appear, they typically show up one to three weeks after exposure. Women may notice unusual vaginal discharge, bleeding between periods, or pain during urination. Men may experience discharge from the penis, burning when they urinate, or pain and swelling in one testicle. Rectal infections can cause pain, discharge, or bleeding regardless of sex. But the absence of symptoms is never a sign the infection is harmless.
Complications for Women
The most significant risk for women is pelvic inflammatory disease (PID), an infection that spreads from the cervix into the uterus, fallopian tubes, and surrounding tissue. About 10 to 15% of women with untreated chlamydia will develop PID. The damage from PID can scar the fallopian tubes, which may lead to chronic pelvic pain, ectopic pregnancy (where a fertilized egg implants outside the uterus, a potentially life-threatening situation), or infertility.
What makes this especially concerning is that chlamydia can cause “silent” infection in the upper reproductive tract, meaning the fallopian tubes can be damaged without a woman ever experiencing pain or other warning signs. By the time someone discovers the problem, often while trying to conceive, the damage may already be permanent.
Complications for Men
Untreated chlamydia in men most commonly leads to epididymitis, a painful inflammation of the tube that carries sperm from the testicle. It can also infect the testicle itself and the prostate. Beyond the pain and swelling, chlamydia can directly damage sperm. Research shows the infection impairs sperm quality, increases DNA fragmentation in sperm cells, and reduces their ability to fertilize an egg. Men in infertile couples have higher rates of chlamydia infection than men in the general population, suggesting a real link between untreated infection and fertility problems.
Risks During Pregnancy
Chlamydia during pregnancy raises the risk of preterm delivery by about 46% and the risk of premature rupture of membranes by about 50%, based on a large population study in Washington State. The infection can also pass to the baby during vaginal delivery, potentially causing eye infections or pneumonia in the newborn. This is why screening is recommended for all pregnant women under 25, with retesting in the third trimester for those at risk and a follow-up test four weeks after treatment.
Joint Inflammation and Other Effects
In a small percentage of cases, roughly 1 to 3%, chlamydia triggers reactive arthritis, a condition where the immune system attacks the joints in response to the infection. The bacteria travel from the urogenital tract to the joints through immune cells in the bloodstream, where they can persist and cause ongoing inflammation. For some people, this becomes a chronic condition. Certain genetic factors, particularly a gene called HLA-B27, appear to make it harder for the body to clear the bacteria, increasing the chance of long-term joint problems.
Untreated chlamydia may also increase your chances of acquiring or transmitting HIV, because the inflammation and tissue disruption caused by the infection make it easier for other pathogens to enter the body.
Treatment Is Simple and Highly Effective
When caught, chlamydia is one of the easiest infections to treat. A standard course of antibiotics taken over seven days has a cure rate of virtually 100% in clinical trials. A single-dose alternative is also available and clears the infection about 97% of the time. Treatment won’t reverse any damage that’s already occurred, but it stops the infection from progressing further.
After treatment, you should be retested in about three months. Reinfection is common, particularly if a sexual partner wasn’t treated at the same time. Both partners need to complete treatment before resuming sexual contact.
Who Should Get Screened
Because chlamydia so often has no symptoms, routine screening is the main way it gets caught early. The CDC recommends annual screening for all sexually active women under 25. Women 25 and older should be screened if they have risk factors like new or multiple sexual partners. All pregnant women under 25 should be tested, along with older pregnant women at increased risk. People living with HIV should be screened at their first evaluation and at least once a year after that.
There are no routine screening recommendations for men in the general population, though testing is straightforward and worth requesting if you have a new partner, multiple partners, or any symptoms. Rectal testing can also be considered based on sexual behavior, regardless of sex.
The gap between how easy chlamydia is to treat and how much damage it can do when ignored is enormous. A simple urine test or swab catches it. A short course of antibiotics eliminates it. The infection only becomes serious when it goes undetected, which is exactly what it’s designed to do.