Medical Conditions - Chlamydia

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The Facts

Chlamydia is the most commonly reported bacterial sexually transmitted infection (STI) in Canada, affecting youths and young adults most often, with young women (15 to 24 years) having the most reported cases.

The infection is named after the bacterium that causes it, Chlamydia trachomatis. Most women and many men who are infected with the bacteria have no symptoms and therefore don’t know they have chlamydia.

Chlamydia is easily treated, but it can sometimes lead to serious complications if it isn’t caught early enough. It is estimated that up to 40% of untreated women will develop symptomatic pelvic inflammatory disease (PID), which can be very painful. The risk of preterm delivery, ectopic pregnancy, or infertility also increases with an untreated chlamydia infection.

Screening for chlamydia is routine for women who are under 25 years old, have a history of a prior sexually transmitted infection, engage in high-risk sexual behavior, or are pregnant. Men are not routinely screened for chlamydia unless they have sex with men or live in an area where there are many cases of chlamydia.


Chlamydia is spread during sexual contact and is highly infectious. It can be transmitted through vaginal, anal, or oral sex. Ejaculation does not have to occur for chlamydia to be spread.

Newborn babies can get infected if their mothers have chlamydia. Nearly half of infants born vaginally (i.e., not by caesarean) to infected mothers will contract chlamydia during delivery. In newborns, chlamydia infections appear as eye problems or respiratory problems rather than the typical genital infections seen in adults.

Symptoms and Complications

People with chlamydia don’t always have symptoms. It is estimated that more than 70% of women and 50% of men won’t show signs of infection. If symptoms start, they will generally show up within 1 to 3 weeks after exposure, but can take as long as 6 weeks to appear. It can infect genital tracts including the cervix, uterus, fallopian tubes, urethra, and epididymis (tube that the stores and carries sperm), as well as the throat, rectum, and eyes.

In men, chlamydia usually starts in the urethra. Symptoms often come and go, or might only be noticed during the first urination of the day. These include:

  • painful burning on urination
  • redness, swelling, burning, and itching around the opening of the penis
  • discharge from the penis, usually milky-white, grey, or yellow in colour
  • pain in the scrotum
  • inflammation of the coiled tube (epididymis) at the back of the testicle that stores and carries sperm, called epididymitis. This will cause testicular pain, tenderness and swelling.
  • prostatitis, an inflammation of the prostate
  • sterility if the infection spreads from the urethra to the testicles

In women, chlamydia usually begins on the cervix. While symptoms are rare in women, they can include:

  • a yellowish vaginal discharge that might have a foul odor
  • painful burning during urination
  • bleeding between periods and after intercourse
  • pain during vaginal intercourse
  • pain in the lower abdomen
  • pelvic inflammatory disease (PID), a serious condition that can permanently damage the fallopian tubes, uterus, and ovaries (this can cause infertility, ectopic pregnancy and chronic pain)

Chlamydia can cause a number of complications in both men and women, depending on the infected site, including:

  • conjunctivitis (pinkeye)
  • pharyngitis (sore throat)
  • rectal pain, bleeding, and discharge
  • reactive arthritis (formerly called Reiter’s syndrome), a type of arthritis that can damage the joints and eyes

In infants with chlamydia, eye infections occur in about 20% to 50% of babies born to infected mothers, and the infection usually occurs within 2 weeks of delivery. If the infection isn’t treated in time, it can lead to scarring of the cornea and permanent damage to vision. About 5% to 30% of babies born to infected mothers will get pneumonia, usually within 2 to 12 weeks after delivery. The chlamydial pneumonia can cause anything from mild symptoms to breathing problems that include a repetitive cough.

Making the Diagnosis

A doctor may use a cotton swab to collect bacteria samples from the cervix, rectum, urethra, or throat. A urine sample may also be taken. These will be sent to a lab and checked for the presence of chlamydia. When testing for chlamydia, doctors will also test for gonorrhea, as many people with one infection will also have the other. 

Since this infection might not have symptoms, your sexual partner(s) could also be infected and should be seen by a doctor in order to also be tested. All sexual partners in the last 60 days should be tested and treated for chlamydia. If there has been no partner over the last 60 days, the most recent partner should be tested and treated. If you are uncomfortable contacting your previous sexual partners, your health care provider can.

Treatment and Prevention

Chlamydia can be cured easily and quickly with antibiotics, sometimes with a single pill. Despite the ease of treatment, thousands of people suffer serious complications each year such as infertility and chronic pain because they had no symptoms or failed to recognize them until it was too late. Don’t wait for symptoms to develop – have routine checkups. Be aware that the risk of acquiring chlamydia increases with the number of sexual partners.

Since chlamydia infection can occur without symptoms, it’s possible to unknowingly transmit this infection to others, or to get it from someone who doesn’t know they have it. Women are more likely to be unaware they have chlamydia. Condoms help decrease the chance of transmission and should be used from the beginning to the end of sex.

Chlamydia in men, women, and babies is treated with various antibiotics. The exact choice depends on the person and the extent of infection.

Even if symptoms aren’t obvious, or if they disappear quickly, you should finish any course of antibiotics for the full length of time prescribed. If symptoms don’t go away within 1 to 2 weeks of completing treatment, see your doctor again. 6 months following the end of treatment, your doctor may want to see you again to make sure the infection is cured even if you are feeling well.

While undergoing treatment, and for at least 1 week after your last dose, you should avoid having sex.

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