Urethral discharge: gonorrhoea or chlamydia? STI testing in Taichung
Discharge, stinging when you urinate, or itching at the opening of the urethra. The colour of the discharge changes the probability. It does not make the diagnosis.
Explained by Dr. Chao-An Chen, urologist, at 昭安泌尿科診所 (Morning Urology Clinic), West District, Taichung.
In short
- Colour only changes the probability. A large amount of yellow-green discharge points to gonorrhoea; a small amount of clear discharge points to chlamydia or Mycoplasma genitalium. Colour cannot replace a test, and the two often occur together.
- With symptoms, you can be tested on the same day. You do not have to wait for a window period. That is the waiting time after an exposure before a test can be trusted.
- A urine test alone is often not enough. After oral or anal sex, the throat and rectum need their own samples. Infections there almost never cause symptoms.
- Do not buy medicine yourself, and do not take old tablets. Medicine taken first can push the bacteria below the level a test can detect without clearing them. The report then reads negative while the infection remains.
- If treatment did not work, resistance is only one of the reasons. The cause may have been a different organism, or an untreated partner may have passed it back.
Urethritis is first sorted into two groups
The first step in the clinic is to sort urethritis into two groups, because the medicine is different.
| Group | Definition | Typical organisms |
|---|---|---|
| Gonococcal urethritis | Neisseria gonorrhoeae is found | Neisseria gonorrhoeae |
| Non-gonococcal urethritis (NGU) | Urethritis is present, but no Neisseria gonorrhoeae is found | Chlamydia, Mycoplasma genitalium, Ureaplasma urealyticum, trichomonas and others |
Non-gonococcal urethritis is not one disease. It is the group that is left after gonorrhoea has been excluded, so a case can only be placed there after the test for gonorrhoea has been done.
The two groups can also exist at the same time. Gonorrhoea with chlamydia is not rare, which is why chlamydia is usually tested for as well when gonorrhoea is confirmed.
What the appearance of the discharge can tell you
| What you see | Points to | But |
|---|---|---|
| Yellow-green, thick, a large amount, most obvious in the morning | Gonorrhoea | Chlamydia can also produce thicker discharge |
| Clear or white, a small amount, sometimes seen only before the first urine of the day | Chlamydia, Mycoplasma genitalium | Early gonorrhoea can also look like this |
| No discharge at all, only itching or stinging | Chlamydia, Mycoplasma genitalium, or a cause that is not an infection | This row has the widest range of causes, so testing matters most here |
Colour can change the probability. It cannot take the place of a test. Gonorrhoea and chlamydia are treated with different medicine, so a wrong guess means the treatment fails.
At the visit, say when the symptoms started, how long ago your last sexual contact was, and what type of sex it was. That decides which sites to sample.
If you have symptoms now, book online or write to the clinic on LINE (@morninguro), so that the sampling can be arranged in one visit.
The organisms involved
Neisseria gonorrhoeae (gonorrhoea). The symptoms are usually the most obvious: yellow-green discharge like pus, and burning when you urinate, about two to seven days after the contact. For gonorrhoea without complications, the current guideline in Taiwan gives priority to a single injection of ceftriaxone into the muscle, not a tablet. See Gonorrhoea: symptoms, testing and treatment (Chinese).
Chlamydia trachomatis. The commonest cause of non-gonococcal urethritis. The incubation period, the time between infection and the first symptoms, is longer, and the symptoms are milder. A high proportion of infected people have no symptoms at all, so they never come for a test, but the infection is still passed on and can still travel up and cause epididymitis. See Chlamydia: the infection that often has no symptoms (Chinese).
Mycoplasma genitalium. This one matters most when symptoms remain after treatment. Its resistance to antibiotics is rising, so it is harder to manage than chlamydia. The sexually transmitted infections treatment guidelines of the US CDC do not recommend routine screening in people with no symptoms, because treating them makes later treatment harder.
Others. Trichomonas vaginalis is a parasite: most men who carry it have no symptoms, and the symptoms are usually clearer in a female partner. Ureaplasma urealyticum, herpes simplex virus and adenovirus can also cause urethritis. Herpes usually comes with painful blisters or ulcers.
Not every case is a sexually transmitted infection
The clinic also sees these symptoms in people with no sexual contact.
- An ordinary bacterial urinary tract infection — often with frequent urination, urgency and lower abdominal discomfort.
- Physical and chemical irritation — cleaning products, lubricants, condom materials, washing too much, or frequent masturbation.
- Inflammation related to the prostate — chronic pelvic pain syndrome is often mistaken for urethritis, but managed in a completely different way.
- Stones or other structural problems in the urinary tract.
The doctor asks about recent sex because the answer changes which tests are needed, not as an assumption about you.
How testing works: what is tested, and from where
Step 1. Confirm that there really is inflammation. Symptoms alone are not enough. Objective evidence is needed: microscopy of the discharge, or the white cell reaction in a first-catch urine sample. Without inflammation, the cause may not be infectious.
Step 2. Confirm which organism it is. A nucleic acid amplification test (NAAT, a PCR-type test) looks for gonorrhoea, chlamydia, Mycoplasma genitalium and trichomonas at the same time, using urine or a swab. With symptoms, it can be done straight away.
Step 3. Confirm whether another site is involved. This step is missed most often. Any part of the body used for sex can be infected:
- Oral sex → throat (gargle or swab)
- Anal sex → rectum (rectal swab)
- Vaginal or penile contact → the genital and urinary tract (first-catch urine)
Infections of the throat and rectum almost never cause symptoms, and a urine test cannot detect them. Even after the urethral symptoms are treated, those sites remain a source of transmission.
Urethritis symptoms are also a good moment to check HIV and syphilis. Anonymous HIV screening under the Taiwan Centers for Disease Control programme can be done here the same day. For this service we do not check your National Health Insurance card or any identity document, so it is open to you regardless of nationality. There is no charge for it. No formal report can be issued, because no identifying information is recorded.
Treatment: wait for the report, or start now?
Both approaches are used. When the symptoms and the exposure history are clear, treatment may be started on clinical judgement while the samples go to the laboratory, and adjusted when the report comes back. When the symptoms are mild or unusual, waiting for the report avoids using the wrong medicine and creating resistance.
Either way, one point decides everything: the samples must be taken before any medicine is started. That is why buying medicine at a pharmacy, or taking old tablets, causes so much trouble. First, it may not work: surveillance by the Taiwan Centers for Disease Control in 2024 showed 96.8% of gonococcal strains in Taiwan resistant to ciprofloxacin, and 74.5% to penicillin. Second, it can make the infection impossible to detect. If you have already taken something, please say what it was and for how many days. It changes how the doctor reads the report.
For non-gonococcal urethritis, guidelines in Taiwan and elsewhere list doxycycline as one of the main options. The medicine, dose and length of the course are decided by the doctor, following the Chinese-language product information approved by the Ministry of Health and Welfare.
When symptoms continue after treatment
There are five common reasons, handled in completely different ways, so taking more antibiotics on your own is not advised.
- The organism was never the one that was treated. Most often, Mycoplasma genitalium was not covered.
- Resistance. Resistance in Mycoplasma genitalium has clearly risen, and the plan is adjusted according to the test results.
- Re-infection. The partner was not treated at the same time, so the infection comes back.
- Another site was not treated. The infection in the throat or the rectum is still there.
- It is not an infection at all. When symptoms continue and the tests stay negative, causes such as chronic pelvic pain syndrome have to be considered.
Only one of these five is resistance. The other four mean the treatment was aimed at the wrong target, so a stronger antibiotic is usually not the next step. Three questions normally show the direction: has there been sex since the treatment, was the partner treated, and was the throat tested. If you were treated somewhere else, please bring the earlier prescription and reports.
Does the partner need treatment too?
Yes, and this decides whether the infection comes back. Gonorrhoea and chlamydia may cause no symptoms at all in a partner, especially infection of the cervix in women, and of the throat or rectum in anyone. If only one side is treated, it usually returns to you within a few weeks.
During treatment, all forms of sex should be avoided, including oral and anal sex, until both people have finished treatment and the doctor confirms that it is fine. If you find it hard to tell your partner, the clinic can give you a written testing recommendation to pass on.
Being tested in Taichung
This clinic is listed on two registers published by the Taiwan Centers for Disease Control, under medical institution code 3503241524. They are two separate services.
- Anonymous HIV screening — a rapid blood test. There is no charge for it, and no National Health Insurance card or identity document is checked.
- Anonymous syphilis screening for young people aged 24 or under, and for students — a rapid test with its own eligible group, supplied according to the kits distributed by the agency.
The symptoms on this page are not covered by those two services, which test for HIV and syphilis only. Gonorrhoea, chlamydia, Mycoplasma genitalium and trichomonas need a separate registration and separate tests, with the sampling sites decided by where sex took place. Both can be handled the same day. If you are not enrolled in Taiwan’s National Health Insurance, the consultation and tests are self-paid. Costs are explained at the consultation.
Please bring your passport or resident certificate; it is needed to create the medical record. We are required by law to report certain infections to the health authority. Your personal information is protected by the Communicable Disease Control Act, Article 10. The clinic uses separate consulting rooms, so you do not need to explain your visit in the waiting area.
Gonorrhoea, chlamydia, Mycoplasma genitalium and trichomonas are grouped together in clinical teaching in Taiwan as the discharge-type sexually transmitted infections. In the 2025 certification course for friendly clinics, run by the Taiwan Urological Association and co-organised by the Taiwan Centers for Disease Control, the session on that group was given by Dr. Chao-An Chen. This is an individual doctor’s teaching experience, not a qualification of the institution.
Common questions
I have already taken antibiotics for a few days. Can I still be tested?
Yes, but please say what you took and for how many days. The doctor needs that history to judge whether the report can be trusted, and the test may need to be repeated later.
The symptoms went away on their own. Do I still need to do anything?
Yes. Relief of the acute symptoms does not mean the infection has cleared. Chlamydia in particular can stay in the body without symptoms, travel up and cause epididymitis, and it remains infectious.
Related pages
Appointments and access
Consultations are conducted in Mandarin, and can also be conducted in English.
昭安泌尿科診所 (Morning Urology Clinic)
No. 98, Boguan 2nd St., West District, Taichung City 403, Taiwan（403 臺中市西區博館二街98號）
Consulting hours: Monday to Saturday (closed Sunday). Online booking is open 24 hours.
This page was produced by 昭安泌尿科診所 (Morning Urology Clinic). Medical content last updated: August 2026 (same as the Traditional Chinese version). English version published: 4 September 2026. Medically reviewed by Dr. Chao-An Chen, urologist.
Sources: Workowski KA, et al. Sexually Transmitted Infections Treatment Guidelines, 2021. MMWR Recomm Rep. 2021;70(4):1-187 / Taiwan Centers for Disease Control and Infectious Diseases Society of Taiwan, clinical guideline on syphilis and gonorrhoea in adults in Taiwan, first edition, August 2025 / Taiwan Centers for Disease Control, antimicrobial resistance surveillance for gonorrhoea (2024 analysis) / Jensen JS, et al. European guideline on Mycoplasma genitalium infections. Later figures published by the agency take precedence over the 2024 figures quoted here.
This page provides general medical information and does not replace an individual diagnosis or treatment plan. The sampling sites, medicine and follow-up are decided by a doctor after assessing your history, symptoms and test results.