Chlamydia : Swiss AIDS Federation


Chlamydial infection is caused by bacteria (Chlamydia trachomatis); it is among the most common sexually transmitted infections in Europe.

How is chlamydia transmitted?

Chlamydia is transmitted through oral, vaginal or anal intercourse. The bacteria reside on the mucous membranes. Semen or vaginal fluid do not contain bacteria that could cause a chlamydial infection.

What are possible symptoms and consequences?


  • Unusual vaginal discharge
  • Vaginal itching
  • Burning sensation during urination
  • Lower abdominal pain
  • Pain or bleeding during intercourse
  • Irregular menstruation
  • Anal itching or discharge


  • Whitish penile discharge, especially in the morning
  • Pain, burning sensation during urination
  • Testicular pain
  • Anal itching or discharge

All the mucous membranes involved in sexual activity – vagina, male urethra, anus/rectum, throat – can transmit chlamydia. In most cases, the infection remains undetected. But left untreated, a chlamydial infection can have long-term consequences even if there are no symptoms initially. In women, it can lead to pelvic infections or blocking of the fallopian tubes – with possible consequences ranging from abdominal pregnancy to infertility. Men may, in rare cases, experience an epididymal inflammation (the epididymis is a part of the testicle) with subsequent sterility.

A chlamydial infection during pregnancy may lead to premature delivery. During delivery, the baby can contract the infection from the mother and subsequently come down with conjunctivitis or pneumonia.

How is chlamydia tested for?

Testing for a chlamydial infection involves analysing a swab of the respective mucosa (vagina, anus, throat, male urethra). Urinalysis is another option, albeit a less reliable one (i.e. less “sensitive”), which means that an infection may not be caught. Furthermore, urinalysis is not suited to test for infections of the anus or throat.

How is chlamydia treated?

The infection can be cured with antibiotics.

Should sexual partners get treatment as well?

The person concerned should consider, together with her or his doctor, where the infection might have come from and whom it might already have been passed on to. Those sexual partners should be informed about the diagnosis, so they can get a medical exam and, if necessary, treatment.

Current sexual partners need to be treated simultaneously to avoid a “ping-pong effect”, whereby partners repeatedly re-infect each other. An additional benefit is the fact that condom use can be dispensed with during simultaneous treatment.

How can the (re-)infection be prevented?

Condoms reduce the risk of getting infected with chlamydia. But an infection is possible despite condom use. It is important to detect and treat an infection early.

If you have changing or multiple sexual partners during the same time period, talk to your doctor or another specialist about sexually transmitted infections (including HIV) and get advice on whether tests may be necessary.

In case of an infection, provides tips on how to inform your partner.

Source: Federal Office of Public Health (FOPH) 2022,

Data protection, cookies and privacy

This website complies with Swiss data protection legislation. More information in our "Privacy Statement".

Data protection, cookies and privacy

This website complies with Swiss data protection legislation. Your privacy is important to us and we process your data in accordance with these regulations. You will find further information in our "Privacy Statement". By using our website, you consent to the processing of your data in accordance with these regulations.

Necessary cookies

Necessary cookies are essential for the proper functioning of our website. They enable you to navigate our website, access secure areas and use basic functions. Without these cookies, our website cannot function properly. They do not store any personally identifiable information and are usually defined as a response to your actions, such as setting your privacy preferences, logging in or filling out forms. You can set your browser to block these cookies, but some parts of our website may not work properly if you do.

Analytics cookies

Analytics cookies help us improve our website by collecting information about how it is used. They help us understand how visitors interact with our website, which pages are most popular and how they get to our website. This information is collected anonymously and in aggregate form, which means that it does not contain any personally identifiable information. We use this information to continually improve our website, its content and the user experience. If you prefer not to allow these cookies, you can disable them, but this may affect the quality of your experience on our website.

Integrated content

We use third-party services to provide features and display useful content on our website. For example, for integrated videos, we use YouTube, which sets cookies to analyse video traffic and improve your user experience. You can accept or reject these cookies.

Your cookie preferences have been saved.