If there's a good end of the STI spectrum to be on, this is it. Chlamydia, gonorrhoea, and syphilis are all bacterial — which means they're fully eliminated by antibiotics. You take the treatment, you follow up, and the infection is gone. That's the headline.

The reason they need their own guide is that each one works a bit differently, has different treatment, and comes with a few specific things worth knowing before you walk out of the clinic.

🔩 Chlamydia

What it is: The most common bacterial STI. Caused by Chlamydia trachomatis.

How it shows up: Mostly, it doesn't — and that's the whole story with chlamydia. It's largely silent, especially in the throat and rectum, which is exactly where the majority of infections in MSM sit. No discharge, no burning, nothing to notice. That silence is why it's the most common bacterial STI going: with no symptoms to prompt a test, it passes between people unseen, and most guys have no idea they're carrying it until a routine swab picks it up.

When it does announce itself, it's usually at the urethra — a clear or cloudy discharge and a burning feeling when you piss, coming on roughly one to three weeks after exposure. Rectal infection occasionally makes itself felt too: pain, discharge, a bit of bleeding, or that nagging urge to go when there's nothing there. Throat infection is almost always symptomless. The takeaway: "I feel fine" tells you nothing here. Feeling completely normal is the single most common way to have chlamydia.

The treatment: Doxycycline, 100mg twice daily for 7 days. Don't shorten the course because you feel fine — you felt fine before you started. Finish it.

Test of cure: A follow-up swab to confirm the infection has actually gone. You usually won't need one — doxycycline clears chlamydia reliably, rectal infection included, so it isn't routine after the standard course. It's worth doing in two cases: if you were treated with azithromycin instead, or if symptoms haven't settled. Either way, wait 3–5 weeks after finishing treatment before you swab, or you can get a false positive. Not sure which applies to you? Ask your clinic.

Sex during treatment: Avoid sex (or use condoms for all acts) until you've finished the full course and had at least 7 days since your last dose. If a test of cure is required, wait for that result.

🔩 Gonorrhoea

What it is: Caused by Neisseria gonorrhoeae. Second most common bacterial STI and increasingly difficult to treat.

How it shows up: More likely to make itself known than chlamydia — but only at the urethra. Classic urethral gonorrhoea is hard to ignore: a thick yellow or green discharge and a real burning when you piss, usually landing two to seven days after exposure. That fast, obvious version is the exception here, not the rule — because the throat and rectum tell a completely different story.

Throat gonorrhoea is almost always silent, and rectal infection is usually symptomless too — though when it does flare, it shows as proctitis: pain, discharge, bleeding, that urge to go when there's nothing there. So a stinging urethra might be your early warning, but the sites most likely to be quietly carrying it are exactly the ones a urine test won't reach. Same rule as chlamydia: feeling fine tells you nothing.

Why it matters more than chlamydia: Two reasons. First, it's developing resistance to antibiotics at a serious rate — standard oral antibiotics no longer work reliably in most countries. Second, throat gonorrhoea is particularly hard to clear and frequently recurs or persists.

The treatment: Ceftriaxone — a single intramuscular injection. Current guidance has been moving toward a 1g dose (up from 500mg) as resistance rises, so the exact dose your clinic uses may vary; either way it's first-line now because oral options can no longer be counted on. It's a quick injection, not a course of tablets — you don't need to worry about remembering pills.

Test of cure: Standard for gonorrhoea, especially throat infections. Throat gonorrhoea is stubborn — a follow-up swab at 2–3 weeks is important, and your doctor may want to retest regardless of whether you have symptoms.

The resistance problem: If this is a recurrent gonorrhoea diagnosis and it doesn't clear after treatment, go back to the clinic. Resistant strains are treated with alternative antibiotic combinations — this needs clinical management, not a second round of the same thing.

Sex during treatment: None (or condoms for all acts) for 7 days after the injection, plus until your partner(s) have been treated. Reinfection from an untreated partner is the most common reason gonorrhoea comes back.

🔩 Syphilis

What it is: Caused by Treponema pallidum. Rates among gay and bisexual men have surged significantly since 2010 and continue to rise in most countries.

How it shows up: This is the tricky one. Syphilis does produce symptoms — but they show up, then clear off on their own, which fools people into thinking the infection went with them. It didn't. The classic first sign is a painless sore, and painless plus tucked inside the rectum or mouth means it's easy to miss completely. So syphilis plays both sides: symptomatic and, in practice, silent — the signs come and go while the infection stays put. The stages below are just a map of that show-up-then-vanish pattern.

Why syphilis is different: It progresses through stages — and the stage you're diagnosed at affects both the treatment and how you talk to partners.

The stages:

Primary: A painless sore (chancre) at the point of entry — could be on the penis, inside the rectum, in the mouth, or on the skin. It disappears on its own after a few weeks. Gone doesn't mean treated.
Secondary: Usually 4–10 weeks after the initial sore. Rash (often on palms and soles — an unusual location), flu-like symptoms, mouth sores, swollen lymph nodes. Also resolves on its own without treatment.
Latent: No symptoms. The infection goes quiet but is still present and doing systemic damage over time — including to the heart, blood vessels, and nervous system.
Tertiary: Rare now that testing and treatment are accessible, but serious. Cardiovascular and neurological damage.

The treatment: A single intramuscular injection of benzathine benzylpenicillin (benzathine penicillin G) — the long-acting depot form. For later-stage syphilis, a course of three weekly injections is standard. If you're penicillin-allergic, doxycycline for 2–4 weeks depending on stage.

Follow-up blood tests: Syphilis is confirmed via blood test (RPR or VDRL titre). After treatment, these titres should fall — the marker clinicians look for is a fourfold drop (for example 1:32 down to 1:8) by 6–12 months, rather than any single number. Your clinic will want follow-up blood tests at 3, 6, and 12 months after treatment to confirm the response. This is important — don't skip these.

The notification window: The notification window is longer than for chlamydia or gonorrhoea — often 3–12 months depending on the stage. Your doctor will advise you on the right window for your situation.

Sex during treatment: No sex (or condoms for all acts) for at least 2 weeks after the injection, and until partners have been treated. Primary and secondary syphilis are highly infectious via the sores and rash.

🛡️ The Testing Picture

Window periods:

Chlamydia and gonorrhoea: Detectable within 1–2 weeks of exposure. If you've had a specific exposure, test at 2 weeks for a reliable result.
Syphilis: The blood test usually turns positive within a few weeks, but it can take up to 12 weeks. A negative test soon after a suspected exposure doesn't fully rule it out — repeat at 12 weeks to be sure. If you suspect a recent exposure — especially if you noticed a sore — tell the clinic so they can factor in timing.

What to ask for: A 3-site test — throat swab, rectal swab, and urine or urethral swab. A urine test alone misses the majority of chlamydia and gonorrhoea infections in MSM. This is worth repeating every time, because clinics don't always offer 3-site automatically.

⚠️ Partner Notification

Bacterial STIs require notification — the windows are defined and the treatment is straightforward, which means notifying partners is genuinely useful to them.

The typical windows:

Chlamydia and gonorrhoea: Partners from the last 3–6 months, or back to the last negative test if that was more recent.
Syphilis: Your doctor will specify based on stage — could be 3 months (primary), 6 months (secondary), or up to 2 years (latent).

The notification script in the guide below applies directly here — keep it factual, keep it short, and frame it as a health advisory rather than an apology.

Anonymous notification services are available in most countries if direct contact isn't possible. Check the relevant country guide.

🟢 The Emotional Side

Bacterial STIs don't carry the same cultural weight as HIV or herpes — but some people still have a strong shame response, particularly to a syphilis diagnosis or a repeated gonorrhoea diagnosis.

Worth naming: having chlamydia or gonorrhoea is not evidence of being reckless. These infections are common precisely because they're silent — the only reliable way to find them is to test, which is exactly what you're doing. A positive result means your system is working.

Syphilis sometimes hits harder emotionally because of the historical connotations. The modern reality: it's a bacterial infection treated with a single injection. The history of syphilis as a devastating disease belongs to the era before antibiotics. That era ended.

Related: