Chlamydia is one of the most common sexually transmitted infections (STIs) in the UK so, if you're thinking of having sex, it's important that you know what Chlamydia is, how you get it and what to do if you've got it...

Whether it causes symptoms or not, chlamydia can damage our insides

What is it?

As many as 10% of sexually active young people have chlamydia. It's caused by tiny bacterium.

You pick it up through unprotected vaginal, oral or anal sex. It affects both sexes.

How do I know if I've got it?

Symptoms include pain while peeing, discharge from the penis or pain in the testicles for boys. Girls may experience tummy ache, bleeding after sex or between periods, pain on peeing, needing to pee more often and/or excess vaginal discharge

Chlamydia can infect the cervix, urethra, anus, throat and the eyes, although this is rare.

Up to 80% of girls and 50% of boys with chlamydia get no symptoms whatsoever. The bugs lurk inside us, but we are none the wiser.

So why does it matter if I get it?

Whether it causes symptoms or not, chlamydia can damage our insides which can then lead to infertility (the inability to have babies). The simple way to protect yourself from infection is to always use a condom. Every time. It's a no brainer.

How can I be sure I haven't got it now?

If you're concerned, take the test - visit your GP, Young People's or Sexual Health clinic, also called a GUM clinic.

You can buy a chlamydia test from some chemists - some stores even offer free testing to 16-24 year olds. You can also 'self-screen', which means testing yourself in private. No intimate examinations or personal questions necessary - you send the sample away to a lab and get the results by post.

Then what?

If your test comes back positive, you'll take a short course of antibiotics. That's it - treatment is very straightforward. It's likely you'll be advised not to have sex for seven days following treatment.

For more information about STIs and chlamydia visit the NHS website.

Click on the link to find a sexual health clinic in your area.

BBC Advice factfiles are here to help young people with a broad range of issues. They're based on advice from medical professionals, government bodies, charities and other relevant groups. Follow the links for more advice from these organisations.