An infection transmissible through some forms of sexual contact, with routes and consequences varying by organism.
Back to the glossarySexual health
Sexually transmitted infection
An infection that can be transmitted through sexual contact; some can also spread through blood, close skin contact, pregnancy, birth or other routes. Many cause no symptoms.
Sexual health
In brief
Different infections, routes and care needs—often without symptoms.
STI is a route-and-health term, not a judgement about identity, cleanliness or relationship structure. Different infections spread in different ways, so risk depends on the activity, body sites, barriers, vaccination, testing and treatment—not a person's appearance or community label.
A change a person notices; many STIs are asymptomatic, and similar symptoms can have non-STI causes.
Contact that may allow transmission; likelihood varies by infection, activity, body site and prevention measures.
Testing people without symptoms or a known diagnosis, according to relevant exposure and guidance.
Routes and body sites
STIs may be bacterial, viral or parasitic and can affect genital, rectal, throat, skin, blood or other sites. A urine or genital test alone may not cover every exposed site.
Some infections spread through fluids, others through skin contact, and some through blood. Barriers reduce particular exposures but do not make every route impossible.
Symptoms and testing
Discharge, pain, sores, rash or bleeding may warrant assessment, but absence of symptoms does not rule out infection. Avoid diagnosing from photographs or symptom lists.
A clinic can select tests based on timing, activity and body sites. Testing too early may require repeat testing after the relevant window.
Prevention and treatment
Options include condoms or other barriers, vaccination, PrEP for HIV, sterile injecting equipment, testing and prompt treatment. The useful combination depends on the infection and person's circumstances.
Antibiotics do not treat viral infections, and unprescribed or leftover medicine can delay correct diagnosis and contribute to resistance.
Communication without stigma
A positive result is health information, not proof of infidelity or irresponsibility. Timing of acquisition may be uncertain, and some infections can persist without symptoms.
Clinics can advise about partner notification and treatment. Share relevant information while respecting confidentiality and avoiding public disclosure.
Non-graphic examples
What the umbrella may include
- Testing despite having no symptoms.
- Requesting throat or rectal tests after relevant exposure.
- Using vaccination and barriers as complementary prevention.
- Seeking assessment for new pain rather than self-diagnosing.
- Using a clinic-supported partner-notification process.
Reviewed 30 August 2026
Keep exploring.
This detailed field note uses the best available evidence without treating one community sample as universal. Evidence limits and UK context are stated where relevant.
Prepared by The UK Kink Guide editorial team. Read the evidence and review methodology.
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