An STI, a sexually transmitted infection, is passed on through sexual contact. The risk is higher without a condom. Not everyone with an STI has symptoms, and that's one of the most important things to know: you can have an STI and not notice it yourself, while still passing it on to someone else. Most STIs are treatable. Here's an overview of the most common ones.
Chlamydia
Chlamydia is the most commonly diagnosed bacterial STI, especially among young people. Most people with chlamydia don't notice anything, and in these cases the infection often clears up on its own without causing damage.
Possible symptoms:
- pain or a burning sensation when urinating
- bleeding from the vagina during or after sex, outside of your period
Treatment: testing and treatment only happen if there are symptoms, using antibiotics. Without symptoms, testing at public health clinics is generally no longer necessary since 2025, as research shows the likelihood of harm in these cases is very small.
Gonorrhea
Gonorrhea presents differently depending on where the infection is located.
Possible symptoms:
- in the penis: usually symptomatic, such as discharge
- in the vagina: often no symptoms, meaning people may not know they have it
Treatment: antibiotics, usually given as an injection. Because the bacterium is becoming increasingly resistant to certain antibiotics, a combination of two medications is often used.
Syphilis
Syphilis progresses in stages, with different symptoms at each stage.
Possible symptoms (first stage):
- a painless sore or ulcer on the penis, vagina, anus, or mouth, which disappears on its own after a few weeks
Possible symptoms (later stage, if untreated):
- spots on the body
- flu-like symptoms, such as fatigue and headache
- with a long-untreated infection: damage to the heart, brain, or nervous system
Treatment: penicillin, in most cases given as a single injection. The earlier treatment starts, the better.
Genital herpes
Many people carry the herpes virus without ever developing symptoms.
Possible symptoms:
- painful blisters or sores on the penis, vagina, anus, or mouth
Once in the body, the virus doesn't go away, but symptoms can lessen or stay away after the first outbreak.
Treatment: there's no treatment that removes the virus, but antiviral medication can reduce symptoms and shorten the duration of an outbreak.
HPV and genital warts
HPV is a virus that most sexually active people contract at some point. It usually clears up on its own without symptoms.
Possible symptoms:
- small, usually painless bumps (genital warts) on the penis, vagina, or anus
Some types of HPV are linked to an increased risk of cervical cancer and other cancers, these are different types from the ones that cause warts.
Treatment: genital warts don't always need to be treated, they often go away on their own, though this can sometimes take a while. If they're bothersome, a cream, freezing, cauterization, or a minor procedure are options. A vaccine exists against the cancer-causing types of HPV, which is free in the Netherlands for young people up to age 18.
When should you get tested?
If you're sexually active, it's a good idea to get tested regularly regardless of symptoms. On top of that, get tested if you have symptoms, after sex without a condom, or if a partner turns out to have an STI. Most STIs can only be reliably detected after about two weeks. You can get an STI test through your doctor or, often free of charge, at a public health clinic.
If you're unsure or have questions about your risk, your doctor or the STI clinic at your local public health service (GGD) can give you personalized advice.
