Chlamydia is a sexually transmitted infection caused by a bacterium. It can be transmitted through sexual contact. All people who are sexually active may be at risk for chlamydia.

Chlamydia can infect the urethra (the tube that allows urine and semen to pass out of the body), cervix, rectum, throat and eyes. Many people with a chlamydia infection have no symptoms. If symptoms do occur, they usually appear two to six weeks after infection. Symptoms can include vaginal pain and bleeding, painful urination, and an abnormal discharge from the vagina, urethra or rectum.

To test for chlamydia, samples are taken from the sites of suspected infection and tested for the presence of the bacteria. Chlamydia can be treated and cured using antibiotics.

Chlamydia can increase the risk of sexual transmission of HIV.

Correct and consistent condom use reduces the risk of chlamydia transmission.

The words we use here – CATIE is committed to using language that is relevant to everyone. People use different terms to describe their genitals. This text uses medical terms, such as vagina and penis, to describe genitals. Cisgenderi people can often identify with these terms. Some transgenderii people may use other terms, such as front hole and strapless. CATIE acknowledges and respects that people use words that they are most comfortable with.

Key messages on chlamydia for clients are available here.

What is chlamydia?

Chlamydia is a sexually transmitted infection (STI) caused by the bacterium Chlamydia trachomatis. The bacterium infects the “wet” linings (mucous membranes) of the body. Chlamydia can infect the genital tracts, including the cervix, uterus, fallopian tubes, urethra (the tube that allows urine and semen to pass out of the body) and epididymis (a tube in the testicle that stores and carries sperm). It can also infect the throat (pharynx), anus and rectum. In addition, it can infect the eyes through contact with infected discharge.¹,²,³

How is chlamydia transmitted?

Chlamydia can be transmitted through sexual contact and sharing of sex toys. Transmission occurs when secretions from infected mucous membranes or semen of a person with a urethral infection comes into contact with the mucous membranes of another person.

Condomless penetrative vaginal sex and anal sex are the highest-risk behaviours for the transmission of chlamydia.

Chlamydia can be transmitted when a person who has the infection in their mouth or throat performs oral sex on another person or when a person performs oral sex on a person who has a genital infection. Oral-anal contact (rimming) can transmit chlamydia as well.

Shared sex toys can also transmit chlamydia. It is theoretically possible to transmit chlamydia through a hand job or fingering if infected fluids are present.

Chlamydia can be passed during childbirth if the newborn has come into contact with infected vaginal discharge or fluid.¹,²,³,

Who is at risk?

Chlamydia is the most common notifiable STI in Canada. A notifiable disease must be reported to public health authorities when an infection is confirmed by a clinic, doctor or laboratory. All people who are sexually active, including people who experience sexual violence, may be at risk for chlamydia. The majority of reported cases of chlamydia occur in people under the age of 30. The highest reported rates have been among females aged 15 to 24. Gender differences in reported rates of chlamydia are likely due, in part, to higher testing rates among females.

Some individuals are at increased risk of chlamydia infection: people who have had condomless sex with a new sexual partner or more than two sexual partners in the past year and people who have had previous STIs.

There are higher rates of chlamydia among injection drug users, prisoners, sex trade workers and street youth. Reported rates of chlamydia among Aboriginal people are higher when compared to national rates, and rates are highest in the northern territories.¹,,,,


Many people with chlamydia have no symptoms. If symptoms do occur, they usually appear two to three weeks after infection (the incubation period) but it can take as long as six weeks.

Infection of the cervix: Symptoms may include an unusual discharge (a fluid that flows out of the opening of the vagina), unusual vaginal odour, pain during vaginal intercourse, and bleeding between menstrual periods. If the infection spreads to the uterus and fallopian tubes, symptoms such as lower abdominal pain, fever and nausea may occur.

Infection of the urethra: Symptoms may include a yellow or white watery or milky discharge, a painful burning sensation during urination, urethral itching, and testicular pain and swelling.

Note that the symptoms of chlamydia may vary for trans persons if they have had bottom surgery and depending on the type of surgery.

Infection of the rectum: Symptoms may include rectal pain, discharge and bleeding.

Infection of the throat: Symptoms may include a sore throat.

Infection of the eye: A chlamydia infection of the eye results in a condition called conjunctivitis (also known as pink eye). The symptoms include itchy red eyes and a green, white or yellow discharge that crusts over the eye.¹,²,³


Untreated chlamydia infection of the cervix can spread to the uterus and fallopian tubes and cause pelvic inflammatory disease (PID). This can result in chronic abdominal pain, infertility and an increased risk of ectopic pregnancy (a potentially serious complication of pregnancy where the embryo implants outside the uterus).

Untreated chlamydia in the urethra can result in inflammation of the epididymis (called epididymitis). The epididymis is a tube in the testicle that stores and carries sperm. Epididymitis can result in infertility; however, this is a relatively rare occurrence.

Untreated chlamydia infection of the rectum can lead to proctitis, an inflammation of the lining of the rectum, which can become chronic.

An untreated eye infection (conjunctivitis) caused by chlamydia can cause scarring of the cornea.

Untreated chlamydia can also lead to the development of a form of reactive arthritis that causes joint pain and swelling of the fingers and toes. Most cases resolve spontaneously within six months of onset, but 30% to 50% of individuals with reactive arthritis will develop chronic symptoms.¹,²,³,,¹⁰

Testing and diagnosis (screening)

To screen for chlamydia, samples are taken from the sites of suspected infection and tested for the presence of bacteria. Suspected infection in the urinary and genital tracts may involve providing a urine sample or having a swab of the vagina, cervix or urethra taken. If there is a discharge from the urethra or vagina, a swab may be taken of the discharge. If someone has had oral or anal sex, a swab of the throat or rectum may be taken.

There are two primary methods of testing collected samples for chlamydia: NAATS (nucleic acid amplification tests) and cell cultures. NAATS are more sensitive than cultures and result in more diagnoses.

The Public Health Agency of Canada (PHAC) recommends that NAATs be used whenever possible to test urine, urethral or cervical samples. However, if blood or mucous is present in the sample, which can interfere with the accuracy of a NAAT, it is recommended that a cell culture be used. Cell culture tests require the use of endocervical or urethral swabs by a health practitioner. Some research suggests that NAATs are more effective than cell culture in detecting rectal chlamydia. PHAC recommends that only cell culture be used to test throat samples.

People diagnosed with chlamydia should also be tested for gonorrhea because there are high rates of this infection in people who have chlamydia. PHAC also recommends HIV counselling and testing, serological testing for syphilis, and immunization for hepatitis B (if not already immune).¹,²,¹¹

Notification of partners

Chlamydia is a reportable infection in Canada. This means that when an infection is confirmed by a clinic, doctor or laboratory it must be reported to public health authorities. When someone has a confirmed chlamydia diagnosis, they will be asked by the healthcare provider or public health nurse to contact or provide contact information for all their sexual partners in the 60 days before they were tested or noticed symptoms. If the client chooses not to contact their sexual partners, the healthcare provider or public health nurse will attempt to contact the partners and encourage them to test for chlamydia and get treated. PHAC recommends that all notified partners be treated without waiting for test results. In an attempt to retain their anonymity, the name of the original client is not given to sexual partners when they are contacted.¹


Chlamydia can be cured with treatment using antibiotics.

Recommended treatment is either a single dose of azithromycin or a seven-day treatment regimen of doxycycline. Both drugs have similarly high rates of effectiveness. If a person has completed treatment and the symptoms (if any) have disappeared and there is no re-exposure to an infected partner, an additional test (called test of cure) is generally not given. However, because reinfection with chlamydia is common, PHAC recommends that all people with chlamydia be retested six months after treatment has been completed.¹

What about HIV?

Having chlamydia can cause the amount of HIV in the genital and rectal fluids of a person with HIV to increase. This can increase the risk of sexual transmission of HIV.

The impact of effective HIV treatment on the transmission of chlamydia is unclear.

People with untreated chlamydia are also at increased risk for HIV infection.¹²


Correct and consistent use of condoms reduces the risk of transmitting chlamydia. There are two types of condoms available. The external condom (sometimes called the “male” condom) is a sheath made from polyurethane, latex or polyisoprene that covers the penis during sex. The internal condom (also known as the insertive or “female” condom) is a pouch made of polyurethane or a synthetic latex material called nitrile that can be inserted into the vagina or rectum.

Some transgender men may cut a condom or oral dam to fit their genitals.

The use of oral dams or other barriers can reduce the risk of chlamydia during oral sex or rimming.

Using a new condom for sex toys with each partner can reduce the risk of chlamydia transmission by preventing the exchange of bodily fluids.

Someone who is diagnosed with chlamydia should avoid having sex until they have been treated and all symptoms have gone. The notification, testing and treatment of all sexual partners of an individual with chlamydia all help to prevent the spread of further infections.¹,²,³,


i Cisgender – someone whose gender identity aligns with the sex they were assigned at birth

ii Transgender – an umbrella term that describes people with diverse gender identities and gender expressions that do not conform to stereotypical ideas about what it means to be a girl/woman or boy/man in society

(Definitions taken from Creating Authentic Spaces: A gender identity and gender expression toolkit to support the implementation of institutional and social change, published by The 519, Toronto, Ontario.)


This fact sheet was developed in partnership with the Sex Information and Education Council of Canada (SIECCAN).


Condoms for the prevention of HIV and STI transmission – CATIE fact sheet


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  2. Centers for Disease Control and Prevention. Chlamydia – CDC Fact Sheet (Detailed Version); 2015. Available at: [Accessed December 17, 2015.]
  3. American Sexual Health Association. Chlamydia. Available at: [Accessed December 17, 2015.]
  4. BC Centre for Disease Control. Smart Sex Resource. Know Your Chances. Available at: [Accessed December 17, 2015].
  5. Public Health Agency of Canada. Notifiable Diseases On-line: Sexually transmitted and blood borne pathogens, count of reported cases of disease in Canada, all ages, 2012. Available at: [Accessed December 17, 2015.]
  6. Public Health Agency of Canada. Report on Sexually Transmitted Infections in Canada: 2011. Ottawa: Centre for Communicable Diseases and Infection Control, Infectious Disease Prevention and Control Branch; 2014. Available at: [Accessed December 17, 2015.]
  7. Dielissen PW, Teunissen DA, Laggro-Janssen TL. Chlamydia prevalence in the general population: is there a sex difference? A systematic review. BMC Infectious Diseases. 2013;13:534. Available at: [Accessed December 17, 2015.]
  8. Public Health Agency of Canada. Questions & Answers: Inclusive practice in the prevention of sexually transmitted and blood borne infections among ethnocultural minorities. Centre for Communicable Diseases and Infection Control, Public Health Agency of Canada. Available at: [Accessed December 17, 2015.]
  9. Mayo Clinic. Diseases and conditions: Proctitis. Available at: [Accessed December 17, 2015.]
  10. Carter J, Inman R, Whittum-Hudson J, Hudson A. Chlamydia and chronic arthritis. Annals of Medicine. 2012;44(8):784-792.
  11. Gratrix J, Bergman J, Egan C, et al. Prevalence and correlates of rectal-only chlamydia infection at two Canadian STI clinics. Sexually Transmitted Infections. 2013;89:A152–A153.
  12. Kalichman SC, Pellowski J, Turner C. Prevalence of sexually transmitted co-infections in people living with HIV/AIDS: systematic review with implications for using HIV treatments for prevention. Sexually Transmitted Infections. 2011; 87(3):183–190.

Published: 2016