Symptoms include a discharge from the penis or vagina and painful or more frequent urination.
If unnoticed or untreated in women, these infections can result in infertility and an increased risk of a mislocated (ectopic) pregnancy.
DNA tests of a sample of the discharge or of urine can detect chlamydia.
Antibiotics can cure the infection, and sex partners should be treated at the same time.
Using condoms during genital sex can help prevent passing these infections from one person to another.
(See also Overview of Sexually Transmitted Infections Overview of Sexually Transmitted Infections (STIs) Sexually transmitted infection (STI) refers to an infection that is passed through blood, semen, vaginal fluids, or other body fluids during oral, anal, or genital sex with an infected partner... read more .)
Several bacteria, including Chlamydia trachomatis (chlamydiae), Ureaplasma, and Mycoplasma, cause similar diseases, all of which resemble gonorrhea Gonorrhea Gonorrhea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae, which infect the lining of the urethra, cervix, rectum, or throat, or the membranes that cover... read more . Laboratories can identify chlamydiae but have difficulty identifying the other bacteria, so these are sometimes called nongonococcal infections.
Chlamydia is the most commonly reported STI in the United States; over 1.5 million cases were reported in 2020. Because the infection frequently causes no symptoms, twice as many people may actually be infected than are reported to have chlamydia.
Chlamydia and gonorrhea Gonorrhea Gonorrhea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae, which infect the lining of the urethra, cervix, rectum, or throat, or the membranes that cover... read more cause similar symptoms. Both can cause urethral infections (urethritis Urethritis Urethritis is infection of the urethra, the tube that carries urine from the bladder out of the body. Bacteria, including those that are sexually transmitted, are the most common cause of urethritis... read more ) in men and, in women, cervical infections (cervicitis Cervicitis Cervicitis is inflammation of the cervix (the lower, narrow part of the uterus that opens into the vagina). It may be caused by an infection or another condition. Cervicitis is often caused... read more ) or pelvic inflammatory disease Pelvic Inflammatory Disease (PID) Pelvic inflammatory disease is an infection of the upper female reproductive organs (the cervix, uterus, fallopian tubes, and ovaries). Pelvic inflammatory disease is often caused by a sexually... read more (see also Chlamydial Infections and Mycoplasmas Chlamydial Infections and Mycoplasmas ).
Sometimes people have gonorrhea and chlamydia at the same time.
Symptoms of Chlamydia
In men, symptoms of chlamydial urethritis start 7 to 28 days after the infection is acquired during intercourse. Typically, men feel a mild burning sensation in their urethra during urination and may have a clear or cloudy discharge from the penis. The discharge is usually less thick than the discharge in gonorrhea Gonorrhea Gonorrhea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae, which infect the lining of the urethra, cervix, rectum, or throat, or the membranes that cover... read more . There may be only a small amount of discharge and mild symptoms. However, early in the morning, the opening of the penis is often red and stuck together with dried secretions. Occasionally, symptoms are more noticeable with a frequent urge to urinate, painful urination, and a discharge of pus from the urethra.
Many women with chlamydial infection of the cervix have few or no symptoms. But some have frequent urges to urinate, painful urination, and a discharge of yellow pus from the vagina. Sexual intercourse may be painful.
If the rectum is infected, people may have rectal pain or tenderness and a yellow discharge of pus and mucus from the rectum.
Chlamydia can also be spread during oral sex, causing infection of the throat. Chlamydial throat infection usually causes no symptoms.
Without treatment, symptoms lessen within 4 weeks in about two thirds of people. However, chlamydia can have serious long-term consequences for women, even when their symptoms are mild or absent. Thus, detecting and treating the infection are important, even if symptoms are absent.
Did You Know...
In women, complications from chlamydia include
Scarring of the fallopian tubes
Infection of the fallopian tubes (salpingitis)
Infection of the membrane that lines the pelvis and abdominal cavity (peritonitis)
Infection in the area around the liver
The infection may spread up the reproductive tract and infect the uterus, the tubes that connect the ovaries to the uterus (fallopian tubes), and sometimes the area around the ovaries. In some women, the infection spreads to the lining of the pelvis and abdominal cavity (peritoneum), causing peritonitis. These infections are called pelvic inflammatory disease Pelvic Inflammatory Disease (PID) Pelvic inflammatory disease is an infection of the upper female reproductive organs (the cervix, uterus, fallopian tubes, and ovaries). Pelvic inflammatory disease is often caused by a sexually... read more (PID) and cause severe lower abdominal pain and sometimes fever. Sometimes infection concentrates in the area around the liver, in the upper right part of the abdomen, causing pain, fever, and vomiting—called the Fitz-Hugh-Curtis syndrome.
Potential complications of pelvic inflammatory disease include severe infection throughout the body (sepsis), chronic abdominal pain, and scarring of the fallopian tubes. The scarring can cause infertility and mislocated (ectopic) pregnancies Ectopic Pregnancy Ectopic pregnancy is attachment (implantation) of a fertilized egg in an abnormal location, such as the fallopian tubes. In an ectopic pregnancy, the fetus cannot survive. When an ectopic pregnancy... read more .
In men, complications from chlamydia include
Infection of the epididymis
Narrowing (stricture) of the urethra
Chlamydial infections may cause infection of the epididymis (epididymitis Epididymitis and Epididymo-orchitis Epididymitis is inflammation of the epididymis (the coiled tube on top of the testis that provides the space and environment for sperm to mature), and epididymo-orchitis is inflammation of the... read more ). The epididymis is the coiled tube on top of each testis (see figure ). This infection causes painful swelling of the scrotum on one or both sides. The infection may lead to narrowing of the urine passage through the penis (urethra) due to scarring.
Pathway From the Penis to the Epididymis
Occasionally in men, organisms spread up the urethra and travel through the tube that carries sperm from the testis (vas deferens) to infect the epididymis at the top of a testis.
In all people, complications from chlamydia may include
Infection of the membrane that covers the white of the eye (conjunctivitis)
Chlamydial genital infections occasionally cause a joint inflammation called reactive arthritis Reactive Arthritis Reactive arthritis (previously called Reiter syndrome) is a spondyloarthritis causing inflammation of the joints and tendon attachments at the joints, often related to an infection. Joint pain... read more . Reactive arthritis typically affects only one or a few joints at once. The knees and other leg joints are affected most often. The inflammation seems to be an immune reaction to the genital infection rather than spread of the infection to the joints. Symptoms typically begin 1 to 3 weeks after the initial chlamydial infection. Reactive arthritis sometimes is accompanied by other problems, such as changes in the skin of the feet, problems with the eyes, and inflammation of the urethra.
In newborns, complications from chlamydial infection include
Newborns may be infected with Chlamydia during delivery if their mother has a chlamydial infection of the cervix. In newborns, the infection may result in pneumonia (neonatal pneumonia Pneumonia in Newborns Pneumonia is an infection of the small air sacs of the lungs (alveoli) and the tissues around them. This infection may be caused by bacteria, viruses, or fungi. Newborns have various symptoms... read more ) or conjunctivitis (neonatal conjunctivitis Conjunctivitis in Newborns Conjunctivitis is inflammation of the conjunctiva, the membrane that lines the eyelid and covers the white of the eye. Conjunctivitis is caused by bacteria, viruses, or a reaction to chemicals... read more ).
Diagnosis of Chlamydia
Usually, testing of a sample of discharge from the cervix, vagina, penis, throat, or rectum or a sample of urine
Doctors suspect chlamydial, ureaplasmal, and mycoplasmal infections based on symptoms, such as a discharge from the penis or cervix, or risk factors, such as age or high-risk sexual activity.
In most cases, doctors diagnose chlamydia by doing tests that detect the bacteria’s unique genetic material (DNA). Usually, a sample of the discharge from the penis or cervix is used. Sometimes women are asked to use a swab to obtain a sample from their vagina. For some types of these tests, a urine sample can be used. If a urine sample can be used, people can avoid the discomfort of having a swab inserted into the penis or having a pelvic examination to obtain a sample.
If doctors suspect infection of the throat or rectum, samples from those sites may be tested.
Gonorrhea Gonorrhea Gonorrhea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae, which infect the lining of the urethra, cervix, rectum, or throat, or the membranes that cover... read more , which is often also present, can be diagnosed using the same sample. Blood tests to check for human immunodeficiency virus (HIV) infection Human Immunodeficiency Virus (HIV) Infection Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and is treated with antiretroviral medications. If untreated, it can cause... read more and syphilis Syphilis Syphilis is a sexually transmitted infection caused by the bacteria Treponema pallidum. It can occur in three stages of symptoms, separated by periods of apparent good health. Syphilis... read more may also be done.
Screening for Chlamydia
Because chlamydia is so common and because many infected women have no symptoms, tests to screen for chlamydia are recommended for certain sexually active people.
If screening is recommended, it is done even if a person uses condoms consistently. Tests are done using samples taken from the rectum, the urethra, or, if they engaged in oral sex, the throat.
Women are screened annually if they are sexually active and under age 25 or if they are 25 years or older, sexually active, and have one or more of the following risk factors:
A previous STI
Risky sexual activities (such as having a new sex partner or multiple sex partners, using condoms inconsistently when not in a mutually monogamous relationship, or participating in sex work)
A history of incarceration
A partner who participates in risky sexual activities or has an STI
Pregnant women are screened during their first prenatal visit and again during their 3rd trimester if they are at high risk.
Men who have sex with women are not routinely screened, but screening is available if a person requests it and is often offered to all patients at adolescent clinics, STI clinics, and correctional facilities.
Men who have sex with men are screened as follows:
If they are sexually active: At least once a year
If they are at increased risk (those with HIV infection, multiple sex partners, or a partner who has multiple partners): Every 3 to 6 months
Transgender and gender diverse people are screened if they are sexually active and on the basis of their sexual practices and anatomy. For example, all people with a cervix who are under age 25 are screened annually. If they are 25 years or older, people with a cervix should be screened annually if at increased risk. Rectal swab screening is done on transgender and gender diverse people based on reported sexual behaviors and exposure.
Treatment of Chlamydia
Simultaneous treatment of sex partners
Chlamydial, ureaplasmal, and mycoplasmal infections are treated with one of the following antibiotics:
A single dose of azithromycin taken by mouth
Doxycycline, erythromycin, levofloxacin, or ofloxacin taken by mouth for 7 days
If gonorrhea Gonorrhea Gonorrhea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae, which infect the lining of the urethra, cervix, rectum, or throat, or the membranes that cover... read more is possible, that is treated at the same time, usually with an antibiotic given as an injection. Such treatment is needed because the symptoms of the two infections are similar and it is common to have both infections at the same time.
Symptoms may persist or return for one of the following reasons:
Other infections that are also present may be causing the symptoms.
People may have become infected again.
The chlamydiae may be resistant to antibiotics.
In such cases, tests for chlamydia and gonorrhea are repeated, and sometimes tests for other infections are done.
Infected people and their sex partners should abstain from sexual intercourse until at least 1 week after they have completed treatment.
All sex partners who have had sexual contact with infected people in the past 60 days should be tested for chlamydia and other STIs and, if positive, should be treated. If sex partners were exposed to chlamydia within the past 2 weeks, they are treated for it without waiting for test results.
Expedited partner therapy is an option doctors sometimes use to make it easier for sex partners to be treated. This approach involves giving people with chlamydia a prescription or medications to give to their partner. Thus, the sex partner is treated, even if they have not yet seen a doctor. Seeing a doctor is better because then the doctor can check for allergies to medications and the presence of other STIs. However, if the partner is unlikely to see a doctor, expedited partner therapy is useful.
Prevention of Chlamydia
The following general measures can help prevent chlamydial infections (and other STIs):
Safer sex practices, including using a condom Condoms Barrier contraceptives physically block the sperm’s access to a woman’s uterus. They include condoms, diaphragms, cervical caps, contraceptive gels, contraceptive sponges, and spermicides (foams... read more every time for oral, anal, or genital sex
Decreased risk of exposure to STIs by reducing the number of sex partners, not having high-risk sex partners (people with many sex partners or who do not practice safer sex), or practicing mutual monogamy or abstinence
Prompt diagnosis and treatment of the infection (to prevent spread to other people)
Identification of the sexual contacts of infected people, followed by counseling or treatment of these contacts
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.