The myth of "I would know if I had something"
One of the most common misconceptions about STIs is that they always cause noticeable symptoms. The reality is that the majority of people with a sexually transmitted infection have no symptoms at all — or symptoms so mild they are dismissed as something else. This is not unusual or a sign of a mild infection; it is simply how many STIs behave biologically.
Which STIs are commonly asymptomatic?
Chlamydia: approximately 70–80% of women and 50% of men with chlamydia have no symptoms. Gonorrhoea: around 50% of women and 10% of men are asymptomatic. Syphilis: the primary stage sore (chancre) is often painless and may appear in a hidden location. HIV: many people experience a brief flu-like illness at seroconversion, then no symptoms for years. HPV: most infections cause no symptoms and clear on their own, though some strains cause warts or cervical changes. Herpes: many people never recognise their symptoms as herpes, or have such mild outbreaks they are not noticed.
Why does asymptomatic infection happen?
Several factors influence whether someone develops symptoms. These include the site of infection (throat and rectal infections are particularly unlikely to cause symptoms), the strain of the pathogen, the immune response of the individual, and for some infections, the sex and anatomy of the person infected. There is no reliable way to distinguish a symptomatic from an asymptomatic presentation without testing.
The importance of regular testing
Because symptoms cannot be relied upon, regular testing is the only reliable way to know your STI status. The British Association for Sexual Health and HIV (BASHH) recommends annual STI testing for all sexually active people, and every 3 months for anyone with multiple partners or who has condomless sex. Testing is free, confidential, and available at NHS sexual health clinics and via home test kits.