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Chlamydia and Other Nongonococcal Infections


Sheldon R. Morris

, MD, MPH, University of California San Diego

Reviewed/Revised Feb 2023
Topic Resources

Chlamydial infections include sexually transmitted infections of the urethra, cervix, and rectum that are caused by the bacteria Chlamydia trachomatis. These bacteria can also infect the membranes that cover the whites of the eyes (conjunctiva) and the throat. Other bacteria, such as Ureaplasma and Mycoplasma, can also cause infections of the urethra.

  • 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.

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 Gonorrhea . 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.

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 Gonorrhea . 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...

  • Chlamydia is the most commonly reported sexually transmitted infection in the United States.


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 Pelvic Inflammatory Disease (PID) (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 a fallopian tube. In an ectopic pregnancy, the fetus cannot survive. Women with an ectopic... 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.

Male Reproductive Organs

In all people, complications from chlamydia may include

  • Infection of the membrane that covers the white of the eye (conjunctivitis)

  • Reactive arthritis

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 . 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

  • Conjunctivitis

  • Pneumonia

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.

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

  • An antibiotic

  • 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 Gonorrhea 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.

Sex partners

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):

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Azasite, Zithromax, Zithromax Powder, Zithromax Single-Dose , Zithromax Tri-Pak, Zithromax Z-Pak, Zmax, Zmax Pediatric
Acticlate, Adoxa, Adoxa Pak, Avidoxy, Doryx, Doxal, Doxy 100, LYMEPAK, Mondoxyne NL, Monodox, Morgidox 1x, Morgidox 2x , Okebo, Oracea, Oraxyl, Periostat, TARGADOX, Vibramycin, Vibra-Tabs
A/T/S, Akne-mycin, E.E.S., Emcin Clear , EMGEL, E-Mycin, ERYC, Erycette, Eryderm , Erygel, Erymax, EryPed, Ery-Tab, Erythra Derm , Erythrocin, Erythrocin Lactobionate, Erythrocin Stearate, Ilosone, Ilotycin, My-E, PCE, PCE Dispertab , Romycin, Staticin, T-Stat
Iquix, Levaquin, Levaquin Leva-Pak, Quixin
Floxin, Ocuflox
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