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What is chlamydia?
Chlamydia is a Sexually Transmitted Infection (STI) caused by a bacterium (germ). It is the most common STI in the United States and in Boston.

How can a person get chlamydia?
Chlamydia is spread when someone has vaginal or anal sex with someone who is infected. Chlamydia can also be passed from mother to child during birth. It is passed through vaginal fluids and semen.

Who can get chlamydia?
Anyone who is sexually active can get chlamydia. Having unprotected sex (sex without a condom) increases the chance of getting chlamydia. In Boston, women under 25 years of age have the highest rates of chlamydia.


Most people do NOT have symptoms. If symptoms do occur, they may start about 1-3 weeks after being infected. For those who do have symptoms, the most common ones are:

For Women:

  • Unusual discharge (yellowish or whitish fluid) from her vagina 
  • Pain and/or burning when she pees or during sex 
  • Pain in the stomach or back 
  • Bleeding even when it’s not her period 
  • In more serious infections, fever 
  • Symptoms from anal sex may cause pain, discharge or bleeding from the rectum (bum)
For Men:
  • Unusual discharge (thick white or watery fluid) coming from the penis 
  • Pain and/or burning when he pees 
  • Less common symptoms include:  
    • Heavy feeling and/or pain in the testicles  
    • Pain, swelling or redness around the scrotum 
  • ​​​​Symptoms from anal sex may cause pain, discharge or bleeding from the rectum (bum) 

How long can an infected person spread chlamydia?
A person can spread chlamydia to others from the time they become infected (by having unprotected sex with an infected partner) until they are treated. A person can spread chlamydia to others even if they do not have symptoms. If you are taking medicine, do not have sex for 7 days after you finish taking the pill(s). It is important to know that you can get infected with chlamydia many times.


How can I find out if I have chlamydia?
The only way to know for sure if you have chlamydia is to get tested. A healthcare provider may ask for a urine (pee) sample or may wipe the infected area with a swab to test for chlamydia. Some people who have chlamydia may also have gonorrhea. A healthcare provider may test you for both at the same time.

How often should I be tested?
Yearly testing is recommended for all sexually active men and women under 25. More frequent testing should be done:

  • Every time you have a new partner 
  • For people of any age at high risk, including: 
  • Those who have had unprotected sex, sex with multiple partners, or  sex with a new partner 
  • All women during pregnancy 
  • 3 months after treatment for a Sexually Transmitted Infection

To find a place to get tested near you, visit or call the Mayor’s Health Line (MHL) at 617-534-5050 and Toll-Free: 1-800-847-0710


Can chlamydia be treated?
Yes, chlamydia is easily treated. A single dose of antibiotics can cure chlamydia. See your healthcare provider again if you still have symptoms after you have taken your medicine. Alternative medicines are available if you are allergic to the medicine usually prescribed.

Should my partner get treated?
Yes. Recent (within the last 60 days) or regular sex partners must be treated before having sex again so it is best to be treated at the same time. Regulations in Massachusetts allow partners of patients with chlamydia to be treated without needing to be tested. Ask your health care provider about this during your visit and read about Expedited Partner Therap​y (EPT)​​. It is impo​rtant to know that you can get infected with chlamydia many times and if your partner is​ not treated, you can be re-infected.

Related Health Problems:
If left untreated, chlamydia can cause very serious health problems. Women can develop Pelvic Inflammatory Disease (PID) which can cause infertility (unable to have children). Chlamydia can also increase your chances of getting other se​xually transmitted infections, such as HIV or gonorrhea.

To find out more about the health consequences of not getting treated click here​.

​To find out more about chlamydia, see our fact sheet here​.

Boston Public Health Commission
1010 Massachusetts Ave, 6th Floor, Boston, MA 02118.
Phone:(617) 534-5395 Email: