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Do I have an STI?

Have you had unprotected sexual contact, for example sex without using a condom, or oral sex without using a dental dam? If so, then there’s a chance you could have a sexually transmitted infection (STI).

It’s a mistake to fall into the habit of convincing yourself you’ll be ok and hoping for the best. Anyone can get an STI – it doesn’t matter how many times they’ve had sex or how many people they’ve had sex with, we’re all at risk. And remember, you may or may not have symptoms, so that is not a reliable way of knowing if you have an STI or not.

Below are some of the symptoms most commonly associated with STIs. Remember though, without being examined and tested by a health professional, you can’t know for certain what your symptoms are caused by. Use this page as a guide and to be sure, arrange an STI test today

If you have more questions or are worried, you can always ask at your local Brook clinic or other sexual health clinic or GP.

Unusual discharge

Discharge is fluid or mucus that comes out of your body. Some discharge is perfectly normal and we may all experience this from time-to-time. However, if you notice discharge from the vagina, penis or rectum that is unusual for you, it could be an STI.

  • Unusual discharge from the vagina, penis or rectum could be chlamydia
  • Unusual green or yellow discharge from the vagina could be gonorrhoea
  • Unusual green, yellow or white discharge from the tip of the penis could be gonorrhoea
  • A frothy, yellow-green and/or fishy smelling vaginal discharge could be trichomoniasis
  • Thin, white discharge from the penis could be trichomoniasis
  • A white or cloudy discharge from the tip of the penis can be caused by urethritis (this is not an STI but can be a result of an STI)
  • A vaginal discharge that has no smell but is either thick and white (a bit like cottage cheese) or thin and watery could be thrush (this is not an STI)
  • A cottage cheese-like discharge under the foreskin that may smell could be thrush (this is not an STI)
  • Unusual discharge can also be caused by vaginitis (this is not an STI)

Stinging, tingling, burning or itching

  • Burning and itching in the genital area in men could be chlamydia
  • Stinging, tingling or itching in the genital or anal area could be genital herpes
  • Itching, swelling and soreness of the penis in men could be trichomoniasis
  • Itching, irritation or inflammation in the affected areas could be pubic lice (you may also be able to see the lice ad their eggs)
  • Vaginal itching (as well as swelling and soreness could be trichomoniasis
  • Itching (together with swelling and soreness) of the penis could be trichomoniasis
  • Itchy inner thighs in women could be trichomoniasis
  • Itching and soreness around the vagina entrance could be thrush (this is not an STI)
  • Stinging when you wee could be thrush (this is not an STI)
  • If the penis becomes sore, itchy and inflamed, this could be thrush (this is not an STI)
  • Irritation or itching of the vagina can also be caused by vaginitis (this is not an STI)

Painful swelling of penis, testicles or foreskin

  • Painful swelling of testicles could be chlamydia or gonorrhoea (this is rare)
  • Painful swelling of the foreskin could be gonorrhoea
  • Swelling and soreness of the penis could be trichomoniasis
  • The tip of the penis feeling irritated or sore can be caused by urethritis (this is not an STI)

Soreness or swelling of the vagina

Pain, burning or increase in your weeing

  • Pain when peeing could be chlamydia
  • A burning feeling when peeing could be gonorrhoea
  • Pain while weeing (and having sex) in women could be trichomoniasis
  • Pain while weeing (and during ejaculation) in men could be trichomoniasis
  • Needing to wee more often in men could be trichomoniasis
  • A desperate and frequent need to wee but only passing small amounts could be cystitis (this is not an STI)
  • Pain, burning or stinging when you wee is a symptom of cystitis (this is not an STI)
  • Pain when you wee can also be caused by vaginitis (this is not an STI)
  • Wee that is dark, cloudy or smelly or traces of blood when you wee is another symptom of cystitis (this is not an STI but can be a result of an STI)
  • Pain, burning or stinging when weeing in men can be caused by urethritis (this is not an STI)
  • A frequent need to wee in men can be caused by urethritis (this is not an STI)

Irregular bleeding

  • This could be caused by chlamydia
  • Light bleeding or spotting can be caused by vaginitis (this is not an STI)
  • Irregular bleeding pattern may also be due to contraception

Pain or tenderness in the lower abdomen (tummy)

  • Pain or tenderness in the lower abdomen could be gonorrhoea
  • Pelvic and lower abdominal pain could be chlamydia
  • Lower abdominal(tummy) pain in women could be trichomoniasis
  • Pain directly above your pubic area, lower back or abdomen could be cystitis (this is not an STI)
  • Pain or tenderness in the lower abdomen could also be for other reasons such as ectopic pregnancy or ovulation

Pain or bleeding during sex

  • Abdominal pain in women during vaginal sex could be chlamydia
  • Pain during sex (and while weeing) in women could be trichomoniasis
  • Pain during ejaculation (and while weeing) in men could be trichomoniasis
  • Bleeding during or after sex could be chlamydia
  • Pain for women during sex can also be caused by vaginitis (this is not an STI)

A strong, unpleasant smell from the vagina after sex

  • This can be a sign of vaginitis (this is not an STI)

Blisters or sores

  • Small fluid-filled blisters in the genital or anal area, buttocks or tops of the thighs which burst to leave small, red painful sores, could be genital herpes
  • A small painless sore on the vagina, penis or anus could be the first stage of syphilis
  • Blisters or sores could also be molluscum

Black powder in your underwear

  • This could be pubic lice (this is the droppings from the lice)

Brown eggs on pubic or other body hair

Sky-blue spots or very tiny specks of blood on the skin

  • This could be pubic lice and is caused by lice bites

I don't have symptoms

You’d be naive to fall into the trap of thinking "I don’t have any symptoms so I must be fine". STIs don’t work like that unfortunately. Some people won’t ever experience any symptoms, and yet they’re still infected. For others, symptoms can take months to appear. For example:

  • Chlamydia: 75% of women with chlamydia and 50% of men don’t have any obvious signs or symptoms
  • Gonorrhoea: 10% of men and 50% of women with gonorrhoea experience no signs or symptoms 
  • Genital herpes: Many people may not get any visible signs or symptoms
  • HIV: around 80% of people with HIV will experience a short, two week illness soon after getting the virus but this could be confused with flu
  • Syphilis: at first, the symptoms of syphilis are usually mild which may lead to some people ignoring them
  • Pubic lice: can take a few weeks to appear. Some people may not have any symptoms or notice them.
  • Trichomoniasis: 50% of men and women with trichomoniasis will not experience any symptoms.
  • Genital warts: Most people don’t have any visible symptoms and it can be months or even years before genital warts appear

Where can I get tested for STIs?

You can get tested for STIs at:

Like Brook, all of these services are free and confidential. You can search for your nearest sexual health service or visit SXT

STI tests are nothing to worry about. They’re usually quick, simple and relatively painless. Depending on what you’re being tested for, a test usually involves an examination of your genitals, as well as taking a swab from inside the vagina or from the tip of the penis and a urine or blood sample. Find out more about getting tested

How are STIs treated?

Most STIs can be treated with a short course of antibiotics. Some STIs, such as HIV cannot be cured – but they can be treated to prevent them from getting worse.

If you test positive for any STI, your clinic will encourage you to talk to your current partner and sometimes to your previous partners so they can be tested as well. The clinic will help you find the best way to talk to other people if you need to, and can notify even contact them for you through 'partner notification' without even mentioning your name.

How can I protect myself from STIs?

STIs can be caught during oral (licking, kissing or sucking someone's genitals), vaginal or anal sex and some can also be passed through sexual touching and skin-to-skin contact – so the best way to avoid STIs is to use a condom or dam every time you have sex. 

A condom is made of very thin latex (rubber) and is designed to cover the penis in order to stop sexual fluids being transferred between partners which provides protection against STIs and pregnancy.

A dam is a thin square of latex, which can be placed over the genitals or anus for oral sex; they are available from your nearest sexual health service (often called GUM clinics) or you can buy them online.

Even if you are using another method of contraception such as the pill, implant, patch, contraceptive vaginal ring, IUD or IUS – it’s important to use condoms and dams as well to also protect from STIs.

Page last reviewed: November 2015
Next review due: November 2017