The essentials in a few lines
A sexually transmitted infection can be present without producing the slightest symptom: that is the most common
situation, and it is why these infections circulate. Three habits cover most of the risk.
Condoms, including for oral and anal sex, remain the only protection that works against nearly all of
them. Regular testing, at every change of partner and before stopping condoms in a new relationship,
is the only way to detect what cannot be seen. And vaccination protects effectively against three of
them: HPV, hepatitis B and mpox.
Everything else depends on the infection: how long after exposure a test becomes reliable, which sample to ask for,
how long treatment lasts and what complications are possible vary a great deal. Each page below sets out those
details.
The infections, one by one
Twelve detailed pages: what the infection is, how it is transmitted, which signs should prompt a check, which test
to ask for and when, what treatment involves, what happens without it, and what to do after a diagnosis.
Symptoms that warrant a check
Unusual discharge, burning on passing urine, persistent itching, a sore, spot or wart on the genitals or around the
anus, pain during sex, unusual bleeding, tender glands: all of these justify a prompt appointment. But the absence of
symptoms rules nothing out — most infections produce none, and someone who feels perfectly well can be infectious.
When to test
- At every change of partner, and before stopping condoms in a new relationship.
- Once a year for anyone sexually active under 25, with or without symptoms.
- More often with multiple partners, asking for throat and rectal swabs according to your practices.
- Whenever you have symptoms, and if a partner tells you they have been diagnosed.
- In early pregnancy, where several tests are routine.
Once a diagnosis is made
Notifying recent partners is the single most effective step, for them and for you: without it, reinfection is the
rule rather than the exception. Most services will do it on your behalf, anonymously, if the conversation is difficult.
A diagnosis should also prompt a full screen: these infections rarely travel alone.
After a risky encounter
Following a recent exposure carrying a significant risk of HIV transmission, post-exposure
treatment can be prescribed by emergency services. It must begin as early as possible, ideally within four
hours, and is no longer offered beyond 48 to 72 hours. That deadline is the only thing that matters: do not leave it
until tomorrow.
Who to see for this problem?
The page Who to see, and when gives, symptom by symptom, the right professional — family doctor, urologist, gynaecologist, sex therapist, psychologist — and the emergencies that cannot wait.
Further reading
Links to official or reference sources. They open in a new tab.
Page checked in September 2026. The instruments cited can change: if in doubt, confirm with the official source given.
