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.
Sources and evidence type
Manual claim and limitation notes are shown where an individual source audit is complete. Other evidence-type labels are a publisher aid awaiting source-by-source confirmation.
Illustration created using generative AI; not documentary evidence.
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.
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.
Status
Detailed editorial draft
Publisher
The UK Kink Guide
Reviewed
Structured draft present; individual review date not recorded
Evidence
3 cited sources · types labelled below
Jurisdiction
UK-focused general education
Read the rest: evidence, law, safety and sources
STI
An infection transmissible through some forms of sexual contact, with routes and consequences varying by organism.
Symptom
A change a person notices; many STIs are asymptomatic, and similar symptoms can have non-STI causes.
Exposure
Contact that may allow transmission; likelihood varies by infection, activity, body site and prevention measures.
Screening
Testing people without symptoms or a known diagnosis, according to relevant exposure and guidance.
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.
Prepare for an appointment
Questions you could ask a professional
What possible causes should be considered?
Could medicines, treatment, pain, hormones or another condition contribute?
Which symptoms or changes would need urgent review?
What options fit my priorities, access needs and health history?
These prompts do not replace assessment and do not imply that every reader needs professional care.
Continue learning
Take the next step from definition to context.
Continue with independent guidance connecting sexually transmitted infection to evidence, consent, safety, uncertainty and practical decisions.
The UK Kink GuideEvidence-led glossary