Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
About Chlamydia Infections
Chlamydia is a common sexually transmitted infection (STI). It is caused by bacteria called Chlamydia trachomatis. Anyone can get chlamydia. It often doesn't cause symptoms, so people may not know that they have it. Antibiotics can cure it. But if it's not treated, chlamydia can cause serious health problems.
You can get chlamydia during oral, vaginal, or anal sex with someone who has chlamydia. Chlamydia can also be passed to the baby during childbirth.
If you've had chlamydia and were treated in the past, you can get re-infected if you have unprotected sex with someone who has it.
Chlamydia is more common in young people, especially young women. You are more likely to get infected with chlamydia if you don't consistently use a condom or if you have multiple partners.
Chlamydia doesn't usually cause any symptoms. So you may not realize that you have it. But even if you don't have symptoms, you can still pass the infection to others.
If you do have symptoms, they may not appear until several weeks after you have sex with someone who has chlamydia.
Symptoms in women include:
- Abnormal vaginal discharge, which may have a strong smell
- A burning sensation when urinating
If the infection spreads, you might get lower abdominal (belly) pain, pain during sex, nausea, and fever.
Symptoms in men include:
- Discharge from your penis
- A burning sensation when urinating (peeing)
- Pain and swelling in one or both testicles (although this is less common)
If the chlamydia infects the rectum (in men or women), it can cause rectal pain, discharge, and bleeding.
There are lab tests to diagnose chlamydia. Your health care provider may ask you to provide a urine sample. Or your provider may use (or ask you to use) a cotton swab to get a sample from your vagina to test for chlamydia.
You should go to your provider for a test if you have symptoms of chlamydia or if you have a partner who has an STI. If you are pregnant, you should get a test when you go to your first prenatal visit.
People at higher risk should get checked for chlamydia every year:
- Sexually active women 25 and younger
- Older women who have new or multiple sex partners or a sex partner who has an STI
- Men who have sex with men (MSM)
In women, an untreated infection can spread to your uterus and fallopian tubes, causing pelvic inflammatory disease (PID). PID can cause permanent damage to your reproductive system. This can lead to long-term pelvic pain, infertility, and ectopic pregnancy. Women who have had chlamydia infections more than once are at higher risk of serious reproductive health complications.
Men often don't have health problems from chlamydia. Sometimes it can infect the epididymis (the tube that carries sperm). This can cause pain, fever, and, rarely, infertility.
Both men and women can develop reactive arthritis because of a chlamydia infection. Reactive arthritis is a type of arthritis that happens as a "reaction" to an infection in the body.
Babies born to infected mothers can get eye infections and pneumonia from chlamydia. It may also make it more likely for your baby to be born too early.
Untreated chlamydia may also increase your chances of getting or giving HIV.
Antibiotics will cure the infection. You may get a one-time dose of the antibiotics, or you may need to take medicine every day for 7 days. It is important to take all the medicine that your provider prescribed for you. Antibiotics cannot repair any permanent damage that the disease has caused.
To prevent spreading the disease to your partner, you should not have sex until the infection has cleared up. If you got a one-time dose of antibiotics, you should wait 7 days after taking the medicine to have sex again. If you have to take medicine every day for 7 days, you should not have sex again until you have finished taking all of the doses of your medicine.
It is common to get a repeat infection, so you need to get tested again about three months after treatment.
The only sure way to prevent chlamydia is to not have vaginal, anal, or oral sex.
Correct usage of latex condoms greatly reduces, but does not eliminate, the risk of catching or spreading chlamydia. If your or your partner is allergic to latex, you can use polyurethane condoms.
Centers for Disease Control and Prevention
It sits within Infections, Sexual Health Issues, Female Reproductive System and Male Reproductive System.
The lead U.S. institute for this subject is the National Institute of Allergy and Infectious Diseases.
When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.
Research on Chlamydia Infections
256 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.
What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.
Research currently under way
- National Rapid TLC: Testing and Linkage to CareUnity Health Toronto
- Single Arm Trial of Menstrual Cups Among Economically Vulnerable Women to Reduce Bacterial Vaginosis and STIsRush University Medical Center
- A Randomized Controlled Trial of Doxycycline Post Exposure Prophylaxis to Prevent Incident Bacterial STIs Among Women in the United StatesTulane University
- Validation of Chlamydia Diagnostic Codes in TriNetX US EHR DataSanofi
- Clinical Evaluation of Visby Medical Men's Sexual Health TestVisby Medical
- Healthy Expectancy Through Routine Antenatal STI ScreeningAdriane Wynn
Research already completed
- Clinical Study of STI Screening to Prevent Adverse Birth and New-born Outcomes (Philani Ndiphile)Foundation for Professional Development (Pty) Ltd
- A Study of the Cobas® Liat CT/NG/MG Test Versus Current Standard Practice for Managing Participants at Increased Risk of Sexually Transmitted InfectionsHoffmann-La Roche
- Inflammation in Methamphetamine and STIs (IMSTI)University of California, Los Angeles
- Sanitation, Water, and Instruction in Face-washing for Trachoma I/IIUniversity of California, San Francisco
- Azithromycin Compared With Doxycycline for Treating Anorectal Chlamydia Trachomatis Infection Concomitant to a Vaginal InfectionUniversity Hospital, Bordeaux
Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.
Where to read more
Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.
Start Here
- About ChlamydiaCenters for Disease Control and Prevention
Diagnosis and Tests
- Chlamydia TestNational Library of Medicine
Related Issues
- Chlamydia, Gonorrhea, and SyphilisAmerican College of Obstetricians and Gynecologists
- EpididymitisMayo Foundation for Medical Education and Research
Statistics and Research
- FastStats: Sexually Transmitted Diseases (STD)National Center for Health Statistics
Clinical Trials
- ClinicalTrials.gov: Chlamydia InfectionsNational Institutes of Health
Medical subject headings
Clinicians and researchers index this subject under Chlamydia Infections. These are the terms to use when searching medical literature.
This page is built from the MedlinePlus health topic record for Chlamydia Infections, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.