Chlamydia is a sexually transmitted infection (STI). This means chlamydia is passed from one person to another during sexual contact.
Chlamydia is caused by the bacteria Chlamydia trachomatis. Both males and females may have chlamydia without having any symptoms. As a result, you may become infected or pass the infection to your partner without knowing it.
You are more likely to become infected with chlamydia if you have:
Sex without using a condom
Had multiple sexual partners
Been infected with chlamydia before
Most women do not have symptoms. But some have:
Burning when they urinate
Pain in the lower part of the belly, possibly with fever
If you have symptoms of a chlamydia infection, your health care provider will collect a culture or perform a test called a nucleic acid amplification test.
In the past, testing required a pelvic exam by a health care provider. Today, very accurate tests can be done on urine samples or on vaginal swabs a woman can collect herself.
Results take 1 - 2 days to come back.
Your health care provider may also check you for other types of sexually transmitted infections, such as gonorrhea, HIV, syphilis, hepatitis, and herpes.
Even if you have no symptoms, you may need a chlamydia test if you:
Are 25 years old or younger and are sexually active (get tested every year)
Have a new sexual partner or more than one partner
Chlamydia can be treated with antibiotics. Some of these are safe to take if you are pregnant. Common side effects include nausea, upset stomach, and diarrhea.
Both you and your partner need to take the antibiotics and finish all of them, even if you feel better and still have some left. All of your sexual partners must take the antibiotics, even if they do not have symptoms. This will prevent you from passing the infection back and forth.
Because gonorrhea often occurs with chlamydia, treatment for gonorrhea is often given at the same time.
Antibiotic treatment almost always works if you and your partner take the medicines as directed.
If chlamydia spreads into your uterus, it can cause scarring and make it harder for you to get pregnant. You can help prevent this by:
Finishing your antibiotics when you are treated
Making sure your sexual partners also take antibiotics
Talking to your health care provider about being tested for chlamydia and seeing your health care provider if you have symptoms
U.S. Preventive Services Task Force. Screening for chlamydial infection: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2007;147:128-134.
Cynthia D White, MD, Fellow American College of Obstetricians and Gynecologists, Group Health Cooperative, Bellevue, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.