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Chlamydia and gonorrhoea are two of the most common sexually transmitted infections (STIs) in the world, in men and women alike. Because their symptoms overlap, and because many people have no symptoms at all, it's easy to misjudge what's going on. Here's how the two compare, what they have in common, and how a single STI test can find either.
What Is Chlamydia?
Chlamydia is an STI caused by the bacterium Chlamydia trachomatis. It spreads through vaginal, anal and oral sex without a condom, and from mother to baby during birth. It's the most commonly reported bacterial STI, and most people who have it notice nothing.
Having had chlamydia doesn't make you immune. You can catch it again after treatment, often from a partner who wasn't treated. Its main danger is long term: in women it can spread to the womb and fallopian tubes and cause infertility.
What Is Gonorrhoea?
Gonorrhoea (gonorrhea in American English, sometimes called 'the clap') is an STI caused by the bacterium Neisseria gonorrhoeae. It spreads in the same ways as chlamydia. Men with a genital infection often notice symptoms within days, but many women, and most people infected in the throat or rectum, notice nothing.
Untreated, gonorrhoea can cause pelvic inflammatory disease, ectopic pregnancy and infertility, and rarely spreads through the blood to the joints and skin. It's also become resistant to many antibiotics, which the World Health Organization treats as a serious and growing public-health problem.
Similarities Between Chlamydia and Gonorrhoea
1. They spread the same way
Both pass through vaginal, anal and oral sex without a condom, and from mother to baby during birth. Both can infect the urethra, cervix, rectum, throat and, less often, the eyes.
2. Their symptoms overlap
When they do cause symptoms, the two look much alike: pain or burning when peeing, discharge from the penis or vagina, and itching or irritation. In the rectum, either can cause discharge, itching or pain when opening your bowels. In the throat, either can cause a sore throat, though usually neither causes anything. You can't tell them apart by symptoms. Only a test can.
3. Both are often silent
Many people with either infection have no symptoms, which is how they get passed on. Read more in our guide to STIs without symptoms.
4. They often come together
It's common to have both at once. That's one reason they're tested for together, and why a doctor treating one will make sure the other is covered.
5. Both can cause serious complications
Untreated, both can cause pelvic inflammatory disease, ectopic pregnancy and infertility in women, and painful swelling of the testicles (epididymitis) in men. Both also make it easier to catch or pass on HIV.
Differences Between Chlamydia and Gonorrhoea
| Feature | Chlamydia | Gonorrhoea |
|---|---|---|
| Cause | The bacterium Chlamydia trachomatis | The bacterium Neisseria gonorrhoeae |
| How often there are no symptoms | Most people have none | Many women, and most throat and rectal infections, have none; men usually notice it |
| Symptoms in men | Pain when peeing, a clear or cloudy discharge, testicular pain or swelling | Burning when peeing and a white, yellow or green discharge, often obvious; testicular pain or swelling |
| Symptoms in women | Usually none; sometimes unusual discharge, pain when peeing, bleeding between periods or after sex, pelvic pain | Often none; sometimes increased discharge, pain when peeing, bleeding between periods, pelvic pain |
| When symptoms appear | 1–3 weeks after sex, if at all | 1–14 days after sex, if at all; often within a few days in men |
| Usual treatment | Antibiotic tablets (usually doxycycline for 7 days) | An antibiotic injection (usually ceftriaxone) |
| Antibiotic resistance | Not a significant problem | A growing problem worldwide |
| After treatment | Retest about 3 months later | Test of cure 7–14 days after treatment for throat infections; retest about 3 months later |
The practical upshot: gonorrhoea is more likely to be noticed (at least in men), and it needs a specific injection rather than tablets. Taking leftover antibiotics or ones bought without a prescription can fail to cure it and adds to resistance. Chlamydia is more likely to sit silently for months.
How Are Chlamydia and Gonorrhoea Tested?
The same tests find both infections, usually from a single sample.
1. PCR (NAAT) testing
A PCR test, also called a nucleic acid amplification test (NAAT), looks for the bacteria's genetic material (DNA or RNA). It can pick up very small amounts, which makes it the most sensitive test available, and it's the test WHO, CDC and NHS guidelines recommend. One sample can be tested for both infections at the same time, which suits people with symptoms that could be either, and people who have no symptoms but may have been exposed.
2. Urine sample
You give the first part of your urine stream (first-catch urine), ideally having not peed for at least an hour beforehand. The lab runs a PCR test on it to check for infection in the urethra or genitals. It's accurate for that, but it can't detect infection in the throat or rectum.
3. Swabs
A soft swab is wiped over the area that might be infected: the vagina, cervix, tip of the penis, rectum or throat. Which swabs you need depends on the sex you've had. After oral sex, a throat swab; after receptive anal sex, a rectal swab. Many people miss a throat or rectal infection because they only gave urine. Our guide to STIs from oral sex explains why the throat matters.
When to test
If you have symptoms, test straight away. If you don't, test about 2 weeks after the sex you're worried about. A test earlier than that can miss an infection that's still developing. If your partner has tested positive, a doctor may treat you at the same visit without waiting for your result. See what to do if your partner tested positive.
Where to Get Tested for Chlamydia and Gonorrhoea in Bangkok
Public and private hospitals and clinics across Bangkok test for both. If you'd rather keep it private, Ovio's at-home STI testing comes to your home, condo, hotel or office. Choose the date, time, place and tests. A doctor takes the urine sample and any swabs you need, and results come back promptly and confidentially, for Thai and international clients alike.
You can book a chlamydia test or a gonorrhoea test on its own, but most people test for both together from one sample, often alongside HIV and syphilis.
Private STI testing in Bangkok
Ovio can arrange private STI testing at a location that works for you.
Frequently Asked Questions
Which is worse, chlamydia or gonorrhoea?
Neither is harmless. Both can cause infertility if left untreated. Gonorrhoea is harder to treat because of antibiotic resistance; chlamydia is more often silent, so it can do damage for longer before anyone notices.
Can you have chlamydia and gonorrhoea at the same time?
Yes, and it's common. That's why they're usually tested for together.
Can chlamydia turn into gonorrhoea?
No. They're caused by different bacteria. One can't turn into the other, although you can catch both.
Is the treatment the same?
No. Chlamydia is usually treated with a week of doxycycline tablets. Gonorrhoea is usually treated with a ceftriaxone injection. If you have both, you'll be treated for both.
Will a urine test find both?
A urine PCR test finds both in the urethra or genitals. It won't find either in the throat or rectum; you need swabs for those.
Can they go away on their own?
Don't count on it. Symptoms may fade, but the infection can stay and keep causing damage. Both need antibiotics.
Sources
- Chlamydia fact sheet (opens in a new tab)
- Gonorrhoea (Neisseria gonorrhoeae infection) fact sheet (opens in a new tab)
- Sexually Transmitted Infections Treatment Guidelines: Chlamydial Infections (opens in a new tab)
- Sexually Transmitted Infections Treatment Guidelines: Gonococcal Infections Among Adolescents and Adults (opens in a new tab)
- Chlamydia (opens in a new tab)
- Gonorrhoea (opens in a new tab)
ABOUT THIS GUIDE
This guide gives general information and is not personal medical advice.
- Written by
- Kewalee Rujikajorn
- Published
