Chlamydia is one of the most common sexually transmitted infections, and in most cases it produces no symptoms at all. About 75% of women and 50% of men with chlamydia never notice anything is wrong. That’s what makes it so consequential: the infection quietly persists, potentially causing serious damage to your reproductive system, while you feel perfectly fine. The good news is that chlamydia is fully curable with a short course of antibiotics, but the longer it goes untreated, the more harm it can do.
Most People Don’t Have Symptoms
The fact that chlamydia is usually silent is its defining feature. If symptoms do appear, they typically show up several weeks after exposure, not days. Many people carry the infection for months without any sign of it.
When symptoms do develop, they differ by sex. Women may notice abnormal vaginal discharge or a burning sensation when peeing. Men may have discharge from the penis, burning during urination, or pain and swelling in one or both testicles, though testicular symptoms are less common. Rectal infections, which can occur in anyone who has receptive anal sex, sometimes cause rectal pain, discharge, or bleeding, but they’re also frequently silent.
Because most infections fly under the radar, routine screening is the primary way chlamydia gets caught. If you’re sexually active and under 25, or have new or multiple partners, regular testing is the most reliable way to find it early.
What Happens in Your Body Over Time
Left untreated, chlamydia doesn’t just sit harmlessly. The bacteria slowly spread through the reproductive tract, triggering inflammation that can cause lasting structural damage. The timeline varies, but the longer the infection persists, the higher the risk of complications.
In women, the most serious consequence is pelvic inflammatory disease (PID), an infection of the uterus, fallopian tubes, or ovaries. PID develops in roughly 10% to 40% of untreated chlamydia cases. It can cause chronic pelvic pain, and the scarring it leaves in the fallopian tubes increases the risk of ectopic pregnancy (where a fertilized egg implants outside the uterus) and long-term fertility problems. Some women with PID have obvious symptoms like fever and lower abdominal pain. Others have a low-grade version that causes damage without dramatic warning signs.
In men, the main complication is epididymitis, an inflammation of the coiled tube at the back of each testicle. Symptoms include a swollen or warm scrotum, one-sided testicular pain that comes on gradually, painful urination, and sometimes discharge. If the inflammation spreads to the testicle itself, it can occasionally lead to reduced fertility, though this is rare.
Risks During Pregnancy
Chlamydia during pregnancy poses a direct risk to the baby. Data from before routine screening became standard showed that up to 60% of newborns delivered to infected mothers acquired the infection during birth. Of those, about 30% developed an eye infection called neonatal conjunctivitis, typically appearing 5 to 14 days after delivery. It ranges from mild discharge to severe eyelid swelling. Around 15% developed pneumonia. Both conditions require treatment, and at least half of newborns with the eye infection also have the bacteria in their airways. Screening pregnant women for chlamydia and treating it before delivery is the most effective way to prevent these outcomes.
How Chlamydia Is Diagnosed
Testing is simple and highly accurate. The standard test, called a nucleic acid amplification test, works on a urine sample or a swab and detects over 90% of infections while maintaining a specificity above 99%, meaning false positives are extremely rare. This method picks up 20% to 50% more infections than older testing techniques. For most people, the test involves nothing more than peeing in a cup.
Treatment and Recovery
Chlamydia is treated with a week-long course of an oral antibiotic taken twice daily. For people who can’t take that medication, a single-dose alternative is available. Either way, the infection clears reliably. You should avoid sexual contact until you’ve completed the full course of treatment. Your sexual partners also need to be tested and treated, even if they have no symptoms, to prevent passing the infection back and forth.
After treatment, you should get retested three months later. This isn’t because the antibiotics failed. It’s because reinfection is common, often from an untreated partner or a new exposure. That three-month retest catches repeat infections early, before they have time to do damage.
Why Reinfection Is So Common
Having chlamydia once doesn’t give you any immunity. You can get it again immediately after being cured. Reinfection carries the same risks as a first infection, and repeated bouts of chlamydia compound the damage. Each round of inflammation in the reproductive tract adds to scarring, further increasing the risk of fertility problems over time. This is why partner treatment and follow-up testing matter as much as your own course of antibiotics. If your partner isn’t treated, the odds of reinfection within months are high.