Chlamydia

How chlamydia spreads

Chlamydia passes through vaginal, anal or oral sex with someone who has the infection, even if ejaculation does not happen. It can be passed from a pregnant person to the baby during birth. It is not spread by toilet seats, kissing, sharing cups or swimming pools.

It is the most commonly reported bacterial STI in the US, with more than 1.5 million cases reported each year and many more undiagnosed. It is most common in people aged 15 to 24.

Symptoms

Around 7 in 10 women and up to half of men have no symptoms. When symptoms appear, it is usually 1 to 3 weeks after exposure, though they can start much later.

Chlamydia symptoms in women

• unusual vaginal discharge
• burning or pain when urinating
• bleeding between periods or after sex
• pain during sex
• lower belly or pelvic pain, which may mean the infection has spread

Chlamydia symptoms in men

• discharge from the tip of the penis, often clear or cloudy
• burning or pain when urinating
• itching or irritation inside the urethra
• pain and swelling in one testicle (epididymitis)

Infections at other sites

• Rectal: usually no symptoms, but can cause rectal pain, discharge and bleeding. A more aggressive form, lymphogranuloma venereum, causes severe proctitis and swollen groin glands.
• Throat: usually no symptoms.
• Eyes: conjunctivitis from contact with infected fluids.
• Newborns: eye infection (neonatal conjunctivitis) and pneumonia.

Complications

In women

• Pelvic inflammatory disease (PID): infection spreads to the uterus, fallopian tubes and ovaries. It can be silent or cause pain and fever.
• Tubal scarring, leading to infertility, chronic pelvic pain and ectopic pregnancy.
• Perihepatitis (Fitz-Hugh-Curtis syndrome): inflammation around the liver causing right upper belly pain.

In men

• epididymitis, and rarely reduced fertility
• prostatitis

In anyone

• Reactive arthritis: joint pain, eye inflammation and urethritis weeks after infection
• increased risk of getting and passing on HIV

In pregnancy

Untreated chlamydia is linked to preterm birth and can infect the baby during delivery. Pregnant people are screened at the first prenatal visit, and those at risk are rescreened in the third trimester.

Testing

• NAAT (nucleic acid amplification test): the most accurate test. It uses a first-catch urine sample (the first part of the stream) or a swab. Self-collected vaginal swabs are as accurate as clinician-collected ones.
• Rectal and throat swabs for people who have anal or oral sex.
• Results usually take a few days. Some clinics offer rapid tests.
• Testing is usually combined with tests for gonorrhea, and HIV and syphilis testing is offered.

Who should be screened

According to the CDC and USPSTF:

• sexually active women under 25, every year
• women 25 and older with new or multiple partners or a partner with an STI
• pregnant people
• men who have sex with men, at least yearly, at all sites used for sex
• anyone with symptoms or a partner with chlamydia

Treatment

• A 7-day course of doxycycline is the CDC's recommended treatment for most people.
• Azithromycin, a single dose, is used in pregnancy and when a 7-day course is not practical.
• Amoxicillin is an alternative in pregnancy.

After treatment

• Avoid sex for 7 days after a single-dose treatment, or until the 7-day course is finished, and until partners are treated.
• Partners from the past 60 days need testing and treatment. In many US states, expedited partner therapy lets your clinician give you medicine or a prescription for your partner.
• Retest about 3 months after treatment, because reinfection is common.
• Test of cure after about 4 weeks is recommended in pregnancy.

Prevention

• use condoms or dental dams every time
• get tested regularly if you are sexually active, especially under 25 or with new partners
• limit the number of sexual partners
• make sure partners are tested and treated before having sex again
• doxycycline taken after sex (doxy-PEP) reduces chlamydia, gonorrhea and syphilis in some high-risk groups. Ask a clinician if it is appropriate for you

Frequently asked questions

What are the first signs of chlamydia?

Most people have no signs at all. When symptoms appear, usually 1 to 3 weeks after exposure, they include unusual vaginal or penile discharge, burning when urinating, bleeding between periods or after sex, and pain in the lower belly or testicles.

Can chlamydia go away on its own?

Sometimes the body clears it eventually, but this can take months, during which it can cause damage and spread to partners. Because of the risk of infertility and other complications, chlamydia should always be treated with antibiotics.

How long does it take for chlamydia to clear with treatment?

Antibiotics cure chlamydia in more than 95% of people. Symptoms usually improve within a few days. Avoid sex for 7 days after a single dose or until the 7-day course is finished, and until partners are treated, to avoid reinfection.

Can chlamydia cause infertility?

Yes. In women, untreated chlamydia can spread to the fallopian tubes, causing scarring that leads to infertility and ectopic pregnancy. Damage can happen without symptoms, which is why regular screening matters. In men, fertility problems are less common.

Can you get chlamydia from oral sex?

Yes. Chlamydia can infect the throat through oral sex, though throat infections are less common and usually cause no symptoms. Throat infections can be passed on to the genitals of partners. Condoms and dental dams reduce the risk.