Chlamydia is a common sexually transmitted infection (STI) caused by the bacterium Chlamydia trachomatis. It is one of the most frequently reported bacterial STIs, with millions of new cases occurring globally each year. Many individuals with chlamydia do not experience noticeable symptoms, allowing the infection to spread unknowingly among sexually active individuals.
How Chlamydia Spreads
Chlamydia primarily spreads through sexual contact, including vaginal, anal, and oral sex. Transmission can occur even without ejaculation, as the bacteria are present in vaginal fluids and semen. Any contact between the mucous membranes of infected areas and those of a partner can lead to transmission.
The bacteria can also be transmitted through sharing sex toys that are not properly cleaned or covered between uses. Chlamydia is not spread through casual contact like hugging, sharing food or drinks, or sitting on toilet seats. Oral sex can transmit chlamydia, though it is less common than vaginal or anal transmission.
Common Signs and Symptoms
As noted, many infected individuals experience no symptoms. Symptoms, if present, can vary by sex and site of infection. For women, these may include abnormal vaginal discharge, a burning sensation during urination, bleeding between periods or after sex, lower abdominal pain, or pain during intercourse.
For men, symptoms include a clear or cloudy discharge from the penis, painful urination, or pain and swelling in one or both testicles. Chlamydia can also infect other areas of the body depending on the type of sexual contact. Rectal infections may cause pain, discharge, or bleeding from the anus, while throat infections are often asymptomatic but can sometimes lead to a sore throat. Eye infections, or conjunctivitis, can result from contact with infected fluids and may cause redness, pain, and discharge.
What to Do if You’ve Been Exposed or Diagnosed
Testing for chlamydia typically involves providing a urine sample or a swab from the potentially infected area, such as the vagina, cervix, urethra, throat, or rectum. Nucleic acid amplification tests (NAATs) are commonly used to detect the bacteria’s genetic material. Results are often available within a day.
Once diagnosed, chlamydia is treated with antibiotics, usually either a single dose of azithromycin or a seven-day course of doxycycline. It is important to complete the entire course of medication, even if symptoms improve, to ensure the infection is fully cleared. Individuals should avoid all sexual activity for at least seven days after starting treatment and until their symptoms resolve to prevent re-infection or spreading the infection to others. Notifying all recent sexual partners is also important so they can be tested and treated, which helps to stop the chain of transmission and prevents re-infection.
Protecting Yourself and Others
Consistent and correct use of barrier methods, such as condoms, during vaginal, anal, and oral sex lowers the chance of infection. This also applies to using barrier methods with sex toys. While not foolproof, these methods provide substantial protection.
Regular STI testing is another important preventive measure, particularly for sexually active individuals. Annual screening is recommended for all sexually active women under 25 and for older women at increased risk, such as those with new or multiple partners. Sexually active gay or bisexual men should also consider annual testing, and more frequently if they have multiple partners. Limiting the number of sexual partners or practicing abstinence are also ways to reduce the risk of chlamydia and other STIs.
Why Prompt Treatment Matters
Untreated chlamydia can lead to long-term health complications. In women, an untreated infection can ascend from the cervix to the reproductive organs, causing pelvic inflammatory disease (PID). PID can result in chronic pelvic pain, damage to the fallopian tubes, and can increase the risk of infertility and ectopic pregnancies, which are pregnancies outside the uterus.
For men, untreated chlamydia can lead to epididymitis, an inflammation of the coiled tube at the back of the testicles that stores and carries sperm. This can cause pain and swelling and, in some cases, may affect fertility. Chlamydia can also be passed from a pregnant individual to their baby during childbirth, potentially causing eye infections or pneumonia in the newborn. Untreated chlamydia may also increase the likelihood of acquiring or transmitting HIV.