Men tend to arrive at a sexual health clinic with one of two questions. Either something has appeared (a discharge, an ulcer, an itch) and they want to know what it is. Or nothing has appeared, but something happened, and they want to know whether they can safely ignore it.
This article answers both. It works through the symptoms that sexually transmitted infections actually produce in men, what each one narrows the diagnosis down to, which symptoms need same-week attention, and why the silent infections are the ones that do the most damage across Singapore.
Start with the uncomfortable fact
Most sexually transmitted infections in men produce no symptoms whatsoever. The majority of chlamydia infections are silent. Throat and rectal gonorrhoea is usually silent. Early HIV produces, at most, a flu-like illness that is indistinguishable from any other virus. Syphilis produces a painless sore that heals by itself.
That means symptom-watching is a poor screening strategy. It works in reverse: symptoms reliably tell you to see a doctor, but their absence tells you very little. If you have had a new or casual partner and you are relying on feeling fine, you are relying on the least sensitive test available.
Urethral discharge
Discharge from the penis that is not urine or semen is the classic presentation of urethritis, and its character offers a genuine clue.
| Appearance | Most likely | Typical timing |
|---|---|---|
| Thick, yellow or green, profuse | Gonorrhoea | 2-7 days after exposure |
| Thin, clear or white, scant | Chlamydia or mycoplasma | 1-3 weeks after exposure |
| Persistent after treatment | Mycoplasma genitalium, resistant gonorrhoea, reinfection | Variable |
These clues are suggestive, not diagnostic. Co-infection is common enough that testing for chlamydia and gonorrhoea together is standard, and mycoplasma is worth adding when discharge persists after a course of antibiotics. It is not covered by a standard two-organism panel and is a frequent reason for treatment failure.
Discharge is accompanied often, but not always, by dysuria: burning or stinging when passing urine. Men frequently assume this is a urinary tract infection. UTIs are uncommon in younger men with a normal urinary tract, so new dysuria after a new sexual partner should be treated as urethritis until proven otherwise. Read our fuller guide to penile discharge if this is your main concern.
Genital ulcers and sores
Whether an ulcer hurts is the single most useful question.
Painless, single, firm-edged, clean base. This is the classic syphilitic chancre. It appears around three weeks after exposure, sits wherever the bacterium entered (penis, anus, mouth) and heals on its own within a few weeks whether or not it is treated. Its disappearance means nothing; the infection continues. A painless ulcer needs a blood test for syphilis, not reassurance.
Painful, multiple, small blisters that break down into shallow ulcers. This is herpes. The first episode is usually the worst, often with fever and tender groin glands, and recurrences are milder and shorter. Diagnosis is best made by swabbing an active lesion rather than by blood test, so it is worth being seen while something is visible.
Painful, ragged, deep ulcer with a purulent base. Chancroid is rare in Singapore but remains on the differential.
Any genital ulcer warrants a full screen, because ulcerative disease substantially increases HIV transmission risk in both directions.
Lumps and growths
Genital warts are soft, skin-coloured, sometimes cauliflower-textured growths caused by low-risk HPV strains. They appear weeks to months after exposure, are usually painless, and can be single or clustered on the shaft, foreskin, base or around the anus. They are treatable (topical therapy, cryotherapy or electrosurgical wart removal) but recurrence is common because the underlying virus persists in the skin for a period after visible warts clear.
Molluscum contagiosum produces small, firm, dome-shaped papules with a central dimple. It is viral, benign and self-limiting, though treatment shortens the course.
Pearly penile papules and Fordyce spots are normal anatomical variants that men very frequently mistake for warts. Pearly papules form a neat ring around the corona and have been there since adolescence; Fordyce spots are small yellowish sebaceous glands on the shaft. Neither is infectious, neither is transmissible, and neither needs treatment. A two-minute examination settles the question and saves months of anxiety.
Testicular pain and swelling
Pain or swelling in one testicle after unprotected sex is usually epididymitis, inflammation of the tube behind the testis, most often caused by chlamydia or gonorrhoea tracking upward. It builds over a day or two, and the scrotum may be red and warm.
The important exception is testicular torsion: sudden, severe, one-sided testicular pain, often with nausea, sometimes waking a man from sleep. This is a surgical emergency with a window of roughly six hours to save the testicle. Sudden severe testicular pain goes to an emergency department, not to a clinic appointment.
Rashes and skin changes
Secondary syphilis produces a non-itchy rash that classically involves the palms and the soles, an unusual distribution that should immediately raise suspicion. It may come with fever, sore throat, patchy hair loss and widespread swollen glands, and like the chancre it resolves without treatment while the infection continues.
Acute HIV seroconversion, two to four weeks after exposure, can produce fever, sore throat, rash, muscle aches, mouth ulcers and swollen glands. It looks exactly like a bad viral illness, which is why it is almost never recognised at the time. If you have that constellation of symptoms and a plausible exposure two to four weeks earlier, ask specifically for HIV testing that includes p24 antigen or RNA. This is the phase in which viral load is highest and onward transmission is most likely.
Anal and throat symptoms
Rectal infection can cause discharge, pain on passing stool, bleeding, or a sensation of incomplete emptying, but is more often entirely silent. Throat infection with gonorrhoea or chlamydia is silent in the large majority of cases and, at most, produces a mild sore throat.
Neither site is covered by a urine sample. If you have receptive anal sex or perform oral sex, a test panel without throat and rectal swabs will miss infections you actually have. This is one of the most common gaps in real-world testing.
How common is asymptomatic infection, really
The figures are worth stating plainly because they change how a reasonable man should behave after a new sexual contact. Around seven in ten chlamydia infections in men produce no noticeable symptoms at all, and the proportion is similar or higher for rectal and pharyngeal gonorrhoea, which are silent in the clear majority of cases regardless of the site tested. Early syphilis produces a chancre that many men never see, particularly when it sits inside the urethra, in the mouth or around the anus, and it heals on its own within weeks whether treated or not. Acute HIV infection causes a symptomatic illness in only around half of those infected, and even then it is usually mild enough to be dismissed as a cold or a bout of stomach flu.
Put together, this means that a man who tests his behaviour against his symptoms, rather than his exposure, is applying the wrong test. Someone with a single unprotected encounter and no symptoms at all still has a real chance of carrying chlamydia, gonorrhoea or another infection silently, and the only way to know is to test on a schedule that matches the incubation periods of each organism, not to wait and see how he feels.
Testing windows at a glance
Because different infections become detectable at different points after exposure, it helps to know when a test is actually reliable rather than simply available.
| Infection | Earliest reliable test | Notes |
|---|---|---|
| Chlamydia and gonorrhoea (NAAT) | 2 weeks after exposure | Test all exposed sites: urine, throat, rectum as relevant |
| Syphilis (serology) | 6 weeks, confirmed by 12 weeks | Earlier testing can miss a recently acquired infection |
| HIV (fourth-generation antigen/antibody) | 4 weeks, conclusive at 6 weeks | Earlier antigen/RNA testing possible after a defined high-risk exposure |
| Herpes (swab of active lesion) | Any time a lesion is present | Blood tests for herpes are less useful and not routinely recommended for screening |
| B型およびC型肝炎 | 6 to 12 weeks | Relevant after exposure to blood or in men who inject drugs |
Testing too early after a single exposure is one of the most common reasons a man receives a falsely reassuring result and relaxes his guard prematurely. Where an exposure was higher risk, or where anxiety is significant, an initial test at two weeks followed by a confirmatory test at six to twelve weeks is a sensible approach, and your doctor can help tailor this to what actually happened rather than a generic schedule.
What to do, and how fast
Same day or emergency: sudden severe testicular pain; fever with genital ulceration and feeling systemically unwell; inability to pass urine.
Within 72 hours: any possible HIV exposure: condom failure, unprotected receptive anal sex, sex with a partner of unknown status. PEP is effective only when started inside 72 hours and works better the earlier it begins. Do not wait for a test result.
Within a week: discharge, dysuria, any ulcer, any new lump, one-sided testicular ache, an unexplained rash. Avoid sex until you have been assessed.
When the window has passed, symptoms or not: chlamydia and gonorrhoea are reliable from two weeks, fourth-generation HIV testing is conclusive at six weeks, and syphilis serology at six to twelve weeks.
A word on the pharmacy shortcut: taking leftover antibiotics, or a course a friend had, is a common and costly mistake. It suppresses symptoms without necessarily curing the infection, makes accurate testing harder for weeks afterwards, and contributes to the gonorrhoea resistance that is making these infections harder to treat regionally.
Getting assessed in Singapore
A symptomatic visit is straightforward: a short history, an examination, a urine sample and usually a blood draw, with swabs added where the exposure history warrants. Most results return in one to three working days, and bacterial infections are cured with a single or short course of antibiotics. Consultation at Hisential is from S$50 after GST.
Hisential offers STI testing and treatment for men across Singapore from 333A Orchard Road, #04-13 Mandarin Gallery, next to Somerset MRT. Patients come to us from every part of the island, and result reviews and follow-up can be handled by telehealth.
Frequently asked questions
How soon after sex do STI symptoms appear?
Gonorrhoea typically within two to seven days, chlamydia one to three weeks, herpes two to twelve days, syphilis around three weeks, and warts weeks to months. Many infections never produce symptoms at all.
Can I have an STI if I have no symptoms?
Yes. Most chlamydia infections, most throat and rectal gonorrhoea, and early HIV and syphilis are commonly symptom-free. Testing is the only way to know.
Is burning urination always an STI?
No, but in a sexually active man with a new partner it is urethritis until proven otherwise. Urinary tract infections are uncommon in men with normal urinary anatomy.
Are the bumps around the head of my penis warts?
Often not. Pearly penile papules form an even ring around the corona and are a normal variant present since adolescence. Warts are irregular, asymmetric and new. An examination distinguishes them quickly.
My symptoms disappeared. Do I still need testing?
Yes. Syphilis chancres and secondary rashes resolve on their own while the infection progresses, and discharge can settle without the bacteria being cleared.
What if symptoms persist after antibiotics?
Consider mycoplasma genitalium, which standard panels do not cover, antibiotic-resistant gonorrhoea, reinfection from an untreated partner, or a non-infectious cause. Go back for reassessment rather than repeating the same treatment.
Related reading
- STIs in Singapore: how they spread and who should get tested
- Penile discharge: a comprehensive guide
- HIV testing types and window periods
References
- Ministry of Health Singapore, Communicable Diseases Surveillance reports
- Department of STI Control (DSC) Clinic, National Skin Centre, clinical guidance
- British Association for Sexual Health and HIV, national guidelines on urethritis and genital ulcer disease
- US Centers for Disease Control and Prevention, STI Treatment Guidelines