Chlamydia - American Sexual Health Association


Chlamydia is common in the U.S. with over 1.5 million cases reported each year (the actual number of cases is likely much higher). Among all age groups, teens and young adults have the highest rates of infection.

Most women with chlamydia (and about half of men) do not experience symptoms. Since symptoms may not be present, the only way to know if a person who may be at risk is infected with chlamydia is to be tested. Annual testing for the infection is recommended for all sexually active women age 25 and under. Yearly testing is also recommended for women over age 25 who have risk factors for chlamydia (e.g., those with new partners and those with multiple sex partners). Depending on exact risk factors, some women may need more frequent screening, and men who might be at risk should also talk with their healthcare providers to see if testing is recommended.

Chlamydia can cured with a simple antibiotic, however, if left untreated, chlamydia can lead to complications such as PID and, potentially, infertility. A person is able to transmit chlamydia to a partner from the time they become infected until treatment is completed.


What is chlamydia?
Chlamydia is a common and curable infection caused by the bacteria chlamydia trachomatis. The bacteria target the cells of the mucous membranes, which are the soft, moist tissues of the body not covered by skin.

Examples of areas that could be infected with this bacteria include:

  • the surfaces of the urethra,vagina, cervix and endometrium
  • the fallopian tubes
  • the anus and rectum
  • the lining of the eyelid
  • and less commonly, the throat

How common is it?
In the United States, chlamydia is the most common bacterial sexually transmitted infection (STI), particularly among sexually active adolescents and young adults. In 2015, a total of 1,526,658 chlamydial infections were reported to the Centers for Disease Control and Prevention (CDC). However, it is estimated that almost 3 million cases actually occurred and as many as one in 10 adolescent females test positive for chlamydia.

How is it transmitted?

  • Chlamydia, like other STIs, is passed from an infected person to a partner through certain sexual activities. Chlamydia is passed primarily during anal or vaginal sex. It is less likely to be transmitted through oral sex.
  • It can be passed when the mucous membrane, the soft skin covering all the openings of the body, comes into contact with the mucous membrane secretions or semen of an infected person. This is what happens during unprotected sex (that is sex without a latex condom) whether vaginal or anal sex.
  • Oral sex is not a common cause of infection with this bacteria. Chlamydia is less likely to be transmitted during oral sex because the bacteria that cause chlamydia prefer to target the genital area rather than the throat. This is why it is unlikely for chlamydia to be transmitted from mouth-to-penis and penis-to-mouth contact, although it is still possible. It is even less likely for transmission to take place from vagina-to-mouth or anus-to-mouth contact. Transmission is not known to occur from mouth-to-vagina and mouth to anus contact.
  • Chlamydia can be passed even if the penis or tongue does not go all the way into the vagina or anus. If the vagina, cervix, anus, penis or mouth come in contact with infected secretions or fluids, then transmission is possible.
  • Even a woman who has not had anal sex can get chlamydia in the anus or rectum if bacteria are spread from the vaginal area, such as when wiping with toilet paper.
  • Eye infections may result when discharge caries the disease into the eye during sex or hand-to-eye contact.
  • Chlamydia is not passed through things like shaking hands or toilet seats.
  • It can also be passed from mother to newborn as the baby passes through the infected birth canal. This can result in eye infections, pneumonia or other complications.
  • In children, chlamydia may be a possible sign of sexual abuse.

What are the symptoms?
It is important to understand that focusing on signs and symptoms is not very useful in determining if someone is infected with chlamydia. First, the symptoms of chlamydia are similar to the symptoms of gonorrhea, and the two infections are often confused. Also, most people with chlamydia do not experience symptoms.

If a person does have symptoms, they usually develop within one to three weeks after exposure to chlamydia. How long a person remains infectious (able to transmit the bacteria to others) is difficult to determine since so many people are asymptomatic. A person must be considered infectious from the time they become infected until treatment is completed.

Men, women and infants

  • Both men and women can experience proctitis (inflamed rectum), urethritis (inflamed urethra) and conjunctivitis (inflamed eyelid).
  • Most infections of the mouth and throat are asymptomatic. If present, symptoms are soreness and redness in the throat or mouth.
  • The most common complications in newborns include conjunctivitis (pink eye) and pneumonia.


  • Most women do not experience any symptoms, but if symptoms are present they may be minor. Symptoms may include:
  • vaginal discharge, or
  • burning sensation during urination.

If the infection spreads to the fallopian tubes, women may experience

  • lower abdominal and lower back pain,
  • pain during intercourse,
  • bleeding between menstrual periods
  • nausea or fever

Men may be asymptomatic or symptoms may be minor. When men do have symptoms, they may experience one or more of the following:

  • pus (thick yellow-white fluid) or watery or milky discharge from the penis
  • pain or burning during urination
  • pain or swelling of the testicle

How is it diagnosed?
There are several different reliable tests for chlamydia. Newer tests, called NAATs (short for nucleic acid amplification tests), are very accurate and easy to take. It may be helpful to speak to your health care provider about what testing options are available (urine or swab tests, for example).

People infected with chlamydia are often also infected with gonorrhea. Therefore, patients with chlamydia are often treated for gonorrhea at the same time, since the cost of treatment is generally less than the cost of testing.

If you live in Alaska, Maryland, or Washington, D.C., you can have a free at-home chlamydia test. Visit for more information.

How is it treated?

There are antibiotic treatments (azithromycin and doxycycline) that are effective in treating chlamydia. Which antibiotic is prescribed is decided by a health care provider, who will take into consideration the particular needs of the patient.

Whatever treatment is prescribed, there are some important points about any treatment:

  • The patient must take all medications as directed.
  • All partners should be examined and treated.
  • The infected person should not have sex until he or she and any partner or partners have been treated and cured.
  • Persons who show symptoms after treatment should be tested again by culture.
  • Infections detected after treatment with one of the recommended treatments more commonly occur because of reinfection rather than treatment failure.
  • Women should be retested three to four months after treatment because of a high rate of reinfection.
  • Because the symptoms of chlamydia are similar to the symptom of gonorrhea, and because a person can be infected with both, doctors will sometimes go ahead and treat people with chlamydia for both infections (chlamydia and gonorrhea). Remember, partners should be examined for infection and treated as well to avoid reinfection.

What does it mean for my health?
If untreated, chlamydia can cause complications in men, women and infants.

Untreated chlamydia infections in women may lead to:

  • Pelvic inflammatory disease (PID), a serious infection of a woman’s reproductive organs. Left untreated, PID can cause infertility.
  • Cystitis (inflammation of the urinary bladder)
  • A condition called mucopurulent cervicitis, characterized by a yellow discharge from the cervix

Untreated chlamydia in men may lead to:

  • Prostatitis (inflammation of the prostate gland)
  • Scarring of the urethra
  • Infertility
  • Epididymitis (inflammation of the epididymis, which is the elongated, cord-like structure that runs along the back of each testes)

Untreated chlamydia in infants may lead to:

  • Blindness
  • Complications of pneumonia, which can include death

How can I reduce my risk?

As with other STIs, there are things people can do to reduce or eliminate the risk of chlamydia. These include the following:

  • Abstinence (not having any sexual contact) is a sure way to avoid infection.
  • Mutual monogamy (having sex with only one uninfected partner, who only has sex with you) is another way to avoid infection.
  • Using latex condoms consistently and correctly for vaginal and anal sex can reduce risk of transmission.
  • Water-based spermicides are not recommended for the prevention of chlamydia. Recent studies have shown that nonoxynol-9 (N-9), which is found in most water-based spermicides, is not effective in preventing chlamydia.

Since chlamydia can be transmitted even if the penis or tongue does not completely enter the vagina, mouth or rectum, using latex condoms at the beginning of sexual contact until there is no longer skin contact is the best form of prevention.

Several barrier methods can be used to reduce the risk of transmission of chlamydia during oral sex. A non-lubricated condom can be used for mouth-to-penis contact. Household plastic wrap, a dental dam, or a latex condom cut-up and opened flat can reduce the risk of transmission during mouth-to-vulva/vagina or oral-anal (rimming) contact.

How do I tell my partner?
Telling a partner can be hard, but keep in mind that most people with chlamydia do not know they have it. It is important that you talk to your partner as soon as possible so she or he can get treatment. Also, it is possible to pass chlamydia back and forth, so if you get treated and your partner does not, you may become infected again.

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