What are STIs?

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An STI is a sexually transmitted infection. You can get infected during sex without noticing anything at all. Do you have an STI? Then you could pass it on to someone else. Many STIs are easy to treat. But remember this: you need to do something about it quickly!

What kind of infection?

Most STIs are caused by bacteria or a virus. But some are caused by tiny bugs called parasites. 

Bacterial STIs

These STIs are caused by bacteria:

Viral STIs

These STIs are caused by a virus:


These STIs are caused by a parasite:


If you have an STI, you may experience symptoms like these:

  • Discharge or pus from the vagina, penis or anus (more than usual). The discharge may be watery, milky, yellowish or greenish and may smell different.
  • A burning sensation, irritation or pain during or after having a pee. Or often needing to pass small amounts of urine.
  • Sores, warts or blisters on the penis, vagina, anus or mouth.
  • Itching in the pubic hair, or on the labia, anus or head of the penis.
  • Swollen glands in the groin.
  • Pain in one or both testicles or the epididymis at the back of the testicle.
  • Pain in the lower abdomen.
  • Pain during sex, or irregular or abnormal blood loss after sex or between 2 periods.

If you have any of these symptoms, it doesn’t necessarily mean you have an STI. The symptom may be caused by something else.

Want to know more about STI testing?

Do you want to know how an STI test is done?
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Make an appointment!

Do you have symptoms, or do you think you have an STI? Don’t ignore it! Make an appointment with your doctor.
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