Commonly known as 'the clap', Gonorrhoea is caused by bacteria and can affect the genitals, throat, eyes and anus.
Symptoms can be highly unpleasant but not everyone gets them. People often don't realise they're infected until they're tested.
Left untreated, it can cause pain and infertility in both men and women.
What is gonorrhoea and how is it caught?
Gonorrhoea is caught during vaginal, anal or oral sex or by sharing sex toys.
Though it can affect the throat, it can't be passed on by kissing an infected person.
Even if there are no obvious symptoms at first, untreated gonorrhoea infections can cause pain and swelling in the abdomen and infertility (problems having children) in both men and women.
It can be passed from mother to baby during childbirth and cause eye infections in the baby.
How can I avoid catching gonorrhoea?
If you're going to have sex, always use a condom (or a dam for oral sex with a woman) and have safer sex.
Not everyone will have symptoms and they're harder to spot in women than in men.
Symptoms, if they do happen, usually show up between 1 and 14 days after infection.
Within a week, men may have lots of green or yellow fluid coming from their penis. They may also have pain or burning when they pee, a rash on the head of the penis and swollen, sore testicles.
Only about 1 in 4 women will have obvious symptoms and they may take longer to appear. Women may have more discharge than normal from their vagina, pain in the abdomen or when peeing. They may bleed between periods, after sex or have irregular or heavy periods.
Gonorrhoea can also infect the anus or throat but these infections often go unnoticed.
Even if you don't have symptoms but have had sex with someone you think has gonorrhoea, you should get tested.
If you have a partner, you should both be tested.
If you have symptoms, a nurse or doctor will take a sample from the affected area using a swab.
Men may be asked for a urine (pee) sample.
Results may be available straightaway or within 14 days.
If the results are positive, you should inform any recent sexual partners so they can be tested too. Sexual health clinics can help you with this.
You can get tested by your GP or at your local sexual health service.
Treatment of 'early' gonorrhoea (i.e. when symptoms first show up) is usually straightforward and is by antibiotics.
Tell the doctor or nurse if you think you picked up the infection while abroad, as they may need to prescribe a different type of antibiotic.
You will be asked to see the nurse or doctor again after a week to make sure the treatment has worked. Don't have sex again until you and your partner have been given the 'all clear'.