7 different types of STIs

Whether you're clued up or don't have a clue, we're here to talk about STIs

We’ve done the research on seven of the most common types of STIs, so you don’t have to. So it’s time to school up, talk more about STIs and find out what you need to know on detecting and helping treat them.

What is an STI?

An STI is a sexually transmitted infection (also known as an STD – sexually transmitted disease) that you can catch from oral, penetrative sexual intercourse or in some cases from close sexual contact. In 2018, there were over 447k diagnoses of an STI which is pretty worrying. Is it because we’re embarrassed to ask our partner the last time they had an STI test? Or is it because there aren’t enough messages out there about safe sex? Whatever it is, we’re here to help…

The seven types of STIs you need to know about

All of these STIs might be different, but one thing is true – if you have an STI, you shouldn’t have sex with a partner until the STI has cleared up as you can cause reinfection and you can infect your partner. Also, if you know you have an STI and haven’t had it treated yet, you should never have sex with a partner without telling them first. 

Either way, you should always use a condom to help prevent STIs, if you think you’ve put yourself at risk of an STI get tested, always get tested before having sex with a new partner and make sure your new partner gets tested, too.


Probably the most well-known STI, especially amongst younger adults, which is why it’s recommended that sexually active adults under 25 (in England) get routinely tested for it once a year or when you change partners. Anyone, whether you’re under 25 or over, can visit a GP or make an appointment at your nearest sexual health or GUM clinic for a free confidential Chlamydia test.

What are the symptoms: most people don’t actually get symptoms which is why you should get routinely tested if you’re sexually active and especially if you change partners a lot. If you do get symptoms they could look like this: pain when peeing, unusual discharge, stomach pain in women, bleeding after sex, bleeding between periods and swelling in the testicles for men.

How do you catch it:  it might seem like an obvious answer – through unprotected sex, but you can also get it from sharing sex toys that aren’t washed (only if the person who used it already has it though), if your genitals come into contact with your partners or infected semen or vaginal fluid gets into your eye (wow).

How do you treat it: if you visit your GP or your nearest sexual health or GUM clinic, they’ll give you a dose of antibiotics – but make sure you finish the course.

What happens if it’s left untreated: it can spread to other parts of your body and lead to long-term health conditions like infertility.

Genital herpes

These look like small blisters that burst, leaving red open sores that usually appear around your genitals, anus, thighs or bum. They are super easy to pass on and once you catch it there’s no cure, as the virus can lay dormant in your body, which means that symptoms can come and go.

What are the symptoms: they might not appear for weeks or even years after you catch herpes and once you get symptoms they should often clear up by themselves but are likely to reoccur. Symptoms include tingling, burning or itching around your genitals, pain when you pee, and in women vaginal discharge that’s unusual for you.

How do you catch it: as well as through sex, you can get it from a cold sore that touches your genitals. It can also be transferred from fingers that have touched a vagina or penis that is infected or by sharing unwashed sex toys with someone who already has herpes. You can still catch herpes from someone who has it even when there are no visible sores or blisters.

How to do you treat it: as there’s no cure you can’t get rid of the virus but you can treat the blisters by keeping the area clean with salt or plain water to help prevent blisters becoming infected, apply an ice pack wrapped in a flannel to soothe any pain or apply petroleum jelly to help reduce pain when peeing.

If you have genital herpes during pregnancy, there’s a risk your baby can develop neonatal herpes which can be fatal but most babies recover with the right treatment. So make sure you see your midwife or GP as soon as possible if you think you have it in pregnancy.

Genital warts

These look like one or more growths or lumps (that are painless) that appear around your vagina, penis or anus. There’s no cure for it but it’s possible for your body to clear the virus (HPV) over time.

What are the symptoms: as well as the lumps, you can also get itching or bleeding from your genitals or anus or you’ll notice a change to your normal flow of pee (for example if it goes sideways when it didn’t before).

How do you catch it: skin-to-skin contact, including vaginal and anal sex, sharing unwashed sex toys with someone who already has it and oral sex – but this is a rare way to catch it.

How do you treat it: depending on what your warts are like you could be offered one of the following treatments – cream or liquid, surgery that involves cutting, burning or using a laser to remove the warts or freezing them off.

How it is different from genital herpes: it’s very different (essentially genital warts can come from human papillomavirus and genital herpes comes from a different virus entirely) it’s just the name that makes it sound like they are similar.

Gonorrhoea (or the clap)

The bacteria that causes this STI is mainly found in discharge from the penis and in vaginal fluid. The bacteria can infect the cervix, the urethra, the rectum and even the throat or eyes (but this is uncommon).

What are the symptoms: about one in 10 infected men and five in 10 infected women don’t experience obvious symptoms, which means it can go untreated for a while. If you do get them they’ll look like this – thick green or yellow discharge from the vagina or penis, pain when urinating, and in women, bleeding between periods.

How do you catch it: it’s easily passed through unprotected sex or sharing unwashed sex toys with someone who already has it.

How do you treat it: if you visit your GP, it’s usually treated with a single antibiotic injection and a single antibiotic tablet.

What happens if it’s left untreated: it can lead to more serious long-term health problems like pelvic inflammatory disease (infection of the womb, fallopian tubes and ovaries) in women or infertility.

If you’re pregnant, the infection can also be passed onto your baby and without treatment can cause permanent blindness in a newborn. Ensure you see your GP straight away if you have it or think you have it.

Pubic lice (or crabs)

These are tiny insects that live on human body hair such as pubic hair, underarm and leg hair, chest, abdomen and back hair, facial hair and/or eyelashes and eyes (but this is quite rare).

What are the symptoms: itching in the areas where pubic lice live, inflammation and irritation, black powder in your underwear, blue spots or small spots of blood on your skin (these are caused by the lice biting you).

How do you catch it: they spread through close bodily contact, but it’s most commonly through sexual contact.

How do you treat it: you should visit your GP who will advise on which treatment you need to use, which will usually be an insecticide cream, lotion or shampoo. You should also get tested for other STIs whilst there.


It’s a bacterial infection that, if left untreated for years, can spread to the brain or other parts of the body and cause serious, long-term problems.

What are the symptoms: small, painless sores on the penis, vagina or anus – they can also show up in your mouth, blotchy red rashes that appear on the palms of the hands or soles of feet, small skin growths, white patches in the mouth, tiredness, headaches, joint pains, a fever and swollen glands in your neck, groin or armpits – yep, that’s quite a lot! But some people can have no symptoms.

How do you catch it: usually by having sex, oral or by sharing unwashed sex toys with someone who has an infected sore. Pregnant women can also pass it onto their unborn baby.

How do you treat it: it won’t go away on its own so you need to see your GP who will test you and give you medicine to help reduce the risk of it spreading or causing serious problems for you later on.


This STI is caused by a tiny parasite called Trichomonas Vaginalis and symptoms usually develop within a month of infection. However, half of people don’t actually get any symptoms, which is why routine check-ups are essential.

What are the symptoms: abnormal discharge from the vagina or penis, producing more than usual that has an unpleasant fishy smell, soreness and itching around the vagina (your thighs might become itchy, too) or head of the penis, and pain or discomfort when having sex or ejaculating or peeing.

How do you catch it: it’s usually spread by unprotected sex or by sharing unwashed sex toys with someone who already is – it can’t be passed on through oral or anal.

How do you treat it: your GP will give you a course of antibiotics – make sure you finish the whole course!

All of these are pretty common, so make sure to wrap it up and don’t be afraid to tell your partner to wrap it up either. We all need to be responsible for our health, which is why we need to start talking openly about sexual health, get regularly tested for STIs and why safe sex is so important. If you need more questions answering about your sexual health, head to Ask Brook. If you are at all concerned about your sexual health, or you think you have an STI, you should speak to your GP or visit your local GUM clinic.