STIs are not moral failures. They are infections — caused by bacteria, viruses, and parasites — that happen to transmit sexually. Most are treatable. Several are curable. All of them are manageable if you know your status and act on it.

This is the map.

The Big Categories

Bacterial STIs (Curable)

These are caused by bacteria and are fully eliminated with antibiotics. The catch: they are largely asymptomatic, so most people don't know they have them.

Chlamydia

  • Most common bacterial STI.
  • Transmission: oral, anal, genital contact.
  • Sites: urethra, rectum (rectal chlamydia is common and almost always without symptoms), throat (pharyngeal chlamydia — almost always without symptoms).
  • Treatment: doxycycline 100mg twice daily for 7 days (or azithromycin 1g single dose, though doxycycline is preferred).
  • If untreated: can cause urethral scarring, epididymitis, and in the long term, fertility issues.

Gonorrhoea

  • Transmission: oral, anal, genital contact.
  • Sites: urethra, rectum, throat, eyes.
  • Notable: gonorrhoea is increasingly antibiotic-resistant. Dual-therapy (ceftriaxone injection + azithromycin, or ceftriaxone alone in many updated guidelines) is now standard in most countries. Oral antibiotics alone are no longer recommended for gonorrhoea.
  • Symptom rate: about 50% symptomatic in the urethra (discharge, burning); rectal and throat infections are almost always silent.

Syphilis

  • Transmission: skin-to-skin contact with sores. The sore can be on the genitals, anus, mouth, or any skin surface.
  • Stages: Primary (painless sore / chancre), Secondary (rash — often on palms and soles, flu-like symptoms), Latent (no symptoms, but still transmissible and infectious), Tertiary (serious systemic damage — rare if treated).
  • Treatment: Penicillin G injection. Highly effective at any stage.
  • The current surge: Syphilis rates among gay and bisexual men have increased substantially across Europe since 2010. Quarterly testing is recommended if you have multiple partners.
❗ Important

Rectal and throat infections are almost always silent. The only way to know is to test. A standard sexual health test that only swabs the urethra misses most infections. You need 3-site testing: urine/urethral swab, rectal swab, throat swab.

Viral STIs (Manageable, Not Curable)

Viruses don't respond to antibiotics. Antiviral medications manage them — suppressing viral load, reducing transmission, and minimising symptoms — but don't eliminate the underlying infection.

HIV

  • Transmission: blood, semen, pre-seminal fluid, rectal secretions, vaginal fluids, breast milk.
  • Highest-risk act: receptive anal sex (approximately 1.4% per act without protection in the highest-risk scenario).
  • Modern reality: with PrEP and treatment, HIV is now a manageable chronic condition. An undetectable HIV-positive person cannot sexually transmit HIV (U=U — see dedicated article).
  • Testing: 4th-generation antigen/antibody tests detect HIV at 28 days. An RNA test can detect it at 10 days.

Herpes (HSV-1 and HSV-2)

  • HSV-1 traditionally causes oral herpes ("cold sores"); HSV-2 traditionally genital. In practice, HSV-1 is increasingly common genitally (often transmitted through oral sex).
  • Transmission: skin-to-skin contact with the affected area, including when no sores are visible (asymptomatic shedding).
  • Reality check: Most people with herpes have no symptoms or very mild ones. It does not define your sex life. Suppressive antiviral therapy (aciclovir, valaciclovir) reduces outbreak frequency and transmission risk.
  • Testing note: Standard sexual health panels often don't include herpes serology. If you want a herpes blood test, request it specifically.

HPV (Human Papillomavirus)

  • Most sexually active people will contract at least one HPV strain in their lifetime. Most clear it without any symptoms.
  • Some strains cause genital warts (types 6 and 11). Other strains (16 and 18, and others) cause cancers — anal, throat, penile.
  • Prevention: Gardasil 9 vaccine is the primary protection. Condoms reduce transmission but don't eliminate it (HPV spreads via skin, not just fluids).
  • See The Vaccine Checklist for HPV data specific to gay and bisexual men.

Hepatitis A, B, and C

  • Hep A: Fecal-oral (rimming). Vaccine-preventable.
  • Hep B: Blood and semen. Vaccine-preventable. Can cause chronic liver disease if untreated.
  • Hep C: Blood-to-blood contact. No vaccine. Curable with direct-acting antivirals. Relevant in fisting, rough anal sex with tissue damage, and shared drug equipment.

Parasitic and Other STIs

Mpox (Monkeypox)

  • Skin-to-skin contact. Has disproportionately affected networks of gay and bisexual men.
  • Vaccine available (Jynneos). See The Vaccine Checklist.

Pubic Lice ("Crabs") and Scabies

  • Skin-to-skin contact. Treated with topical permethrin or oral ivermectin.

Transmission Risk at a Glance

Act HIV risk Bacterial STI risk Herpes / HPV risk
Receptive anal sex (no condom, no PrEP) High High (rectal gonorrhoea, chlamydia) Moderate–high
Insertive anal sex (no condom, no PrEP) Moderate High (urethral gonorrhoea, chlamydia) Moderate
Receptive oral sex Very low–negligible Moderate (throat gonorrhoea) Low–moderate
Insertive oral sex Negligible Moderate (urethral gonorrhoea) Low (herpes via oral contact)
Rimming Negligible Moderate (Hep A, rectal bacteria) Low
Skin-to-skin (groin area) None Low High (herpes, HPV)

The Asymptomatic Problem

The most important thing about this table: most STIs produce no symptoms, especially in the rectum and throat. The absence of symptoms is not evidence of the absence of infection.

This is why the testing protocol matters. You cannot know your status by how you feel.

Stigma and Language

STIs happen to people who have sex. They are infections with established transmission routes — not a reflection of character, hygiene, or how many partners you have.

"Clean" to mean STI-free is stigmatising language — it implies people with STIs are dirty. Say "tested," "negative," "clear" instead. If someone uses "clean" at you, it's worth gently redirecting; it's rarely malicious, usually just inherited language.

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