Chlamydia: the common STI with no symptoms and an easy cure
Last updated September 3, 2026.
Chlamydia is the most common bacterial STI, and its most dangerous feature is that most people with it feel completely fine. Around 70% of women and half of men with chlamydia have no symptoms, while the infection quietly does its damage in the background. It is cured with a short course of antibiotics, testing is a urine sample or swab, and screening exists precisely because you cannot rely on symptoms to find it.
What does it look like when it shows?
When symptoms appear (weeks after exposure), they are subtle: unusual discharge, burning when passing urine, and in women, bleeding between periods or after sex and lower abdominal pain. In men, discharge from the penis and testicular ache or swelling. Rectal infection (usually silent) causes discharge and discomfort; throat infection is typically symptomless. But the honest framing remains: the absence of symptoms means nothing, and the only way to know is a test. That is why screening programs target sexually active under-25s annually, and why a test belongs in every new-relationship chapter.
Why treat something that does not hurt?
Because untreated chlamydia climbs. In women it causes pelvic inflammatory disease in a meaningful share of cases, scarring the fallopian tubes; the consequences are ectopic pregnancy risk and infertility, sometimes discovered only years later when conception fails. In men it can inflame the epididymis and, rarely, affect fertility. It also raises the risk of acquiring or passing HIV. All of this is preventable with a week of antibiotics, which is the strongest argument for testing without symptoms: the damage is silent, and the cure is trivial.
What actually helps?
- Get tested properly: a urine sample or self-taken swab; no examination needed in most cases. Testing is free and routine at sexual health clinics, and home test kits are reliable when used correctly.
- Take the antibiotics: doxycycline 100mg twice daily for 7 days is first-line; azithromycin is the alternative when doxycycline is unsuitable (including pregnancy).
- No sex until done: avoid sex (including with condoms, ideally) until you and your partner have both completed treatment, typically 7 days, or you will pass it back and forth.
- Tell the partners: current and recent partners (usually the last 6 months) need testing and treatment too. Clinics can notify partners anonymously if you prefer.
- Retest in 3 months: reinfection is common enough that guidelines recommend a repeat test about 3 months after treatment, especially under 25.
When is it an emergency?
Chlamydia itself moves at clinic speed. The escalation: severe lower abdominal pain with fever, vomiting, or pain during sex suggests pelvic inflammatory disease, which needs same-day assessment and a longer antibiotic course. Testicular pain and swelling that is sudden and severe is a different emergency (torsion until proven otherwise), not chlamydia. In pregnancy, a positive test deserves prompt treatment and follow-up but is not an emergency. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
Can chlamydia go away on its own?
Occasionally the immune system clears it over many months, but relying on that is a losing bet: while it persists it can silently scar the fallopian tubes, spread to partners, and (rarely) trigger reactive arthritis. Given that the cure is a single week of antibiotics, treatment is always the right call. There is also a testing wrinkle: a test can stay positive for a few weeks after successful treatment from dead bacterial remnants, which is why the 3-month retest rather than an immediate one.
How long after exposure does a test turn positive?
Nucleic acid tests (the standard urine or swab test) usually detect chlamydia within about 1-2 weeks of exposure. Testing earlier can miss a very recent infection, so if the exposure was days ago, clinics typically test now and repeat in 2 weeks, or treat presumptively when a partner is confirmed positive. Symptoms, when they come at all, typically appear 1-3 weeks after exposure, but waiting for symptoms is a bad strategy when most infections never produce them.
Does chlamydia cause infertility?
Untreated, it can. Chlamydia ascending to the uterus and tubes causes pelvic inflammatory disease, and each episode increases the chance of tubal scarring: the mechanism behind tubal infertility and ectopic pregnancy. The key word is untreated. Prompt treatment prevents the damage, which is why screening matters more than symptoms. If you had chlamydia years ago and are now trying to conceive, mention it: a tubal assessment (a dye test called an HSG) can check whether the tubes are open.
Can I get chlamydia again after treatment?
Yes; treatment cures the infection but gives no immunity. Reinfection is common, usually from an untreated partner or a new exposure, which is why both partners must complete treatment before resuming sex and why guidelines recommend retesting about 3 months after treatment. Recurrent chlamydia does not build resistance to the antibiotics; it is almost always a new infection, not a failed treatment. Condoms until both partners are tested and treated is the structural fix.
How do I tell my partner?
Directly and without ceremony works best: it is a common, curable infection, most people have no symptoms, and getting treated protects both of you. Frame it as a health errand, not an accusation; chlamydia can have been carried silently for months or years, so a positive test does not date the infection or prove anything about anyone's behavior. If a direct conversation is impossible, sexual health clinics offer anonymous partner notification, where they contact your partners without naming you.
Is chlamydia testing painful or embarrassing?
No; the modern test is a urine sample or a self-taken vaginal swab you do yourself in private, and no physical examination is needed for most asymptomatic people. Clinics that do this daily are matter-of-fact and non-judgmental by profession. Results typically arrive within days by text. Home test kits ordered online are accurate when the instructions are followed and are a reasonable option if a clinic visit is the barrier.