The silent infection: 6 long-term consequences of chlamydia

Chlamydia is one of the sexually transmitted infections (STIs – sexually transmitted infections). In 2020, an estimated 128.5 million new chlamydia infections were recorded worldwide among adults aged 15 to 49 (WHO, 2023). This STI is one of the most common in Europe and often presents without noticeable symptoms, increasing the risk of long-term untreated consequences. In this article, we will take a closer look at what a chlamydia infection is, explain its possible long-term health effects, and discuss how you can get tested for this STI.

Table of Contents

• What is chlamydia?
• Symptoms of a chlamydia infection
• Long-term consequences of chlamydia
• How can I effectively prevent a chlamydia infection?
• How to treat Chlamydia
• What Are the Risk Factors for Chlamydia?
• Frequently asked questions
• Summary

What is chlamydia?

Chlamydia is a sexually transmitted disease caused by the bacterium Chlamydia trachomatis. This infection occurs most commonly in young adults between the ages of 15 and 24, mainly because new and changing sexual contacts are more frequent in this age group. Both men and women can be affected by this STI, and without appropriate treatment, it can lead to serious health problems (MedlinePlus, 2024).

How is chlamydia transmitted?

The infection is transmitted through:

• unprotected vaginal, anal, or oral sex.
• the shared use of sex toys that have not been cleaned or covered with a new condom.
• genital contact with an infected person, even without penetration (insertion of the penis into the vagina).
• the transmission from an infected mother to the child during birth.
  

Chlamydia infections can occur repeatedly; successful treatment cures the current infection but does not protect against future infections ((Mayo Clinic, 2024).

Symptoms of a chlamydia infection

Chlamydia is often referred to as a “silent infection” because 50 to 70% of those affected usually show no symptoms. This makes the disease particularly insidious and a serious health risk, as many people unknowingly infect others and may develop complications themselves without realizing it.

Although most people do not notice any symptoms, there are still signs that may indicate an infection. An unusual discharge from the vagina or penis can be an initial sign. If you notice these symptoms, do not hesitate to get tested or consult a doctor. The symptoms in men and women as well as common symptoms are listed below:

Source: Cleveland Clinic, 2023

Chlamydia trachomatis can also infect the throat and anus, leading to specific symptoms. Oral infections can cause sore throat and redness, while anal infections may lead to itching, pain during bowel movements, and unusual anal discharge.

Long-term consequences of chlamydia

Without appropriate treatment, a silent, asymptomatic chlamydia infection can lead to serious health problems, ranging from chronic pain to infertility. Below are some of the more severe long-term consequences. Early detection and regular testing for chlamydia are essential.

Pelvic inflammatory disease (PID)

PID is a common long-term complication of chlamydia in women—10 to 15% of women with untreated chlamydia infections are affected. It occurs when the infection spreads from the vagina to the uterus, fallopian tubes, or ovaries. Symptoms may include severe lower abdominal pain, fever, and unusual discharge. If left untreated, PID can lead to chronic pain, abscesses, an increased risk of ectopic pregnancy, and infertility. Sexual partners of women diagnosed with this condition should also be tested and treated for chlamydia to prevent reinfection. A follow-up test should be done 3 months after treatment (NHS, 2022).

Epididymitis

Chlamydia is one of the most common causes of epididymitis, especially in sexually active men under the age of 35. The epididymis is located on the testicles in the scrotum, and the inflammation is characterized by pain, swelling, and tenderness in the testicular area. Over time, this may impair fertility and cause chronic pain (Mayo Clinic, 2023).

Reactive arthritis

Reactive arthritis is a rather rare but serious possible consequence of a chlamydia infection, which can affect both men and women. This form of arthritis typically develops two to four weeks after the initial infection and is marked by symptoms such as pain, stiffness, and swelling in the joints and tendons—most commonly in the knees, feet, toes, hips, and ankles. In addition to joint involvement, other parts of the body may also be affected, such as the eyes (conjunctivitis) and urinary tract. The inflammation can occur in flare-ups, meaning symptoms may subside temporarily before returning (NHS, 2021).

Pregnancy complications

Untreated chlamydia infections during pregnancy increase the risk of premature birth and may result in low birth weight. Furthermore, the infection can be transmitted to the child during delivery, potentially causing eye infections or pneumonia in the newborn. Therefore, pregnant women are often routinely tested for chlamydia, especially if they have risk factors such as new or multiple sexual partners (NHS, 2021).

Infertility

Chlamydia can lead to infertility in both men and women. The infection can cause inflammation and scarring of reproductive organs, which may impair fertility. Although the overall risk of infertility due to a chlamydia infection is less than 1%, the risk increases with the number of infections and the length of time they go untreated (Soa Aids Netherlands, 2022; Cleveland Clinic, 2023).

Increased risk of HIV

People with untreated chlamydia have a higher risk of contracting HIV (human immunodeficiency virus) when exposed to the virus, as chlamydia-related damage to mucous membranes can facilitate HIV transmission (WHO, 2023).

How can I effectively prevent a chlamydia infection?

Preventing a chlamydia infection primarily involves education and preventive measures:

• Use of condoms: Condoms are an effective tool for preventing the transmission of sexually transmitted infections (STIs), but they do not offer complete protection against Chlamydia trachomatis, as the infection can also be transmitted through other forms of close physical contact, such as skin-to-skin contact with infected areas not covered by a condom.
• Open communication with sexual partners: Open communication about STIs and one's sexual health with all sexual partners is essential to reduce the risk of transmission.
• Regular testing: For people with frequently changing sexual partners, it is especially important to get tested regularly for chlamydia and other sexually transmitted diseases. Regular testing allows for early detection and treatment of infections. 

Source: Mayo Clinic, 2024

Want to get an overview yourself?

The chlamydia test from Homed-IQ offers a convenient way to test for chlamydia from the comfort of your home. However, it is important to consider the diagnostic window—that is, the period after infection during which the bacteria are not yet present in sufficient quantity to be detected by tests. Chlamydia cannot be detected immediately after infection. It is therefore recommended to take the test approximately 14 days after possible exposure to avoid false-negative results (i.e., the test indicates no infection even though one is present).

How to treat Chlamydia

Chlamydia is usually treated with antibiotics and may clear within one to two weeks. Take the full course exactly as prescribed, even if symptoms improve, and ask your healthcare provider whether follow up testing is needed to confirm the infection has cleared. You should also be tested for other STIs, as more than one infection can occur at the same time. Antibiotics cure the infection but cannot reverse damage that occurred before treatment, which is why regular screening, prompt medical care for symptoms, and early treatment are important. 

Because chlamydia can recur, avoid sexual contact until treatment is complete and the infection has cleared. Sexual partners from the past three months should be informed, tested, and treated if necessary to prevent reinfection. In the Netherlands, it is possible to anonymously warn your partner with https://partnerwaarschuwing.nl/. In the event of a positive result, Homed-IQ can coordinate a code to be generated to use this service.

Source: Cleveland Clinic, 2023

What Are the Risk Factors for Chlamydia?

Certain behaviors and circumstances can increase the likelihood of contracting chlamydia. Key risk factors include:

• Being sexually active before the age of 25
• Not using condoms or using them incorrectly
• Having new or multiple sexual partners
• Changing sexual partners before knowing about a chlamydia infection
• Limited use of STI prevention, testing, and treatment services

Source: Mayo Clinic, 2024

Frequently asked questions

How long does chlamydia last if I don’t treat it?

As already mentioned, it often happens that a person has no chlamydia symptoms at all. Once chlamydia is treated, it usually resolves within 14 days. In case there are no symptoms or the symptoms are ignored, a chlamydia infection can last for a very long time. The danger in this is that an untreated chlamydia infection can cause long-term side effects (NHS, 2024).

What happens after I get treated for chlamydia?

During your treatment with antibiotics, it is advised to avoid sexual intercourse to eliminate the risk of infecting your partner, even if you no longer have symptoms. Even after your treatment is over, it is recommended to wait another week before having sex again. This way, you make sure that the infection is cleared and you no longer can infect your partner. Since it is still possible to be reinfected with chlamydia, it is recommended to do another self-test approximately 12 weeks after treatment. 

Source: MedlinePlus, n.d.; CDC, n.d.; KHealth, n.d.

There are several common myths about how chlamydia spreads. Chlamydia does not spread through everyday contact such as kissing, hugging, sharing towels or cutlery, using toilet seats, or bathing and swimming in shared facilities. Chlamydia is transmitted through sexual contact with an infected person, including vaginal, anal, or oral sex, through contact with infected genital fluids (Communicable Diseases Agency, 2025).

Can you get Chlamydia multiple times?

Yes, you can. While Chlamydia is easy to treat, it is not possible to become immune against Chlamydia bacteria and multiple infections can occur (CDC, 2022). Therefore, it is crucial to use a condom when having sex with a partner who has not been recently tested, and get tested yourself on a regular basis.

Summary

Chlamydia is one of the most common sexually transmitted infections and is caused by the bacterium Chlamydia trachomatis. It is transmitted through unprotected vaginal, anal, or oral sex and through the shared use of unclean sex toys. A huge challenge is that many chlamydia infections are asymptomatic, meaning the infection can be unknowingly transmitted and left untreated. If left untreated, chlamydia can lead to serious long-term consequences such as pelvic inflammatory disease, infertility, and an increased risk of HIV infection.