STI testing

Why routine testing

Most STIs cause no symptoms, so testing is the only way to know. Screening is not an accusation, a sign of distrust, or evidence of anything about your behaviour — it is maintenance, like a dental check.

How often

• Sexually active with new or multiple partners: every 3–6 months.
• Men who have sex with men, or anyone on PrEP: every 3 months, at all exposed sites, per CDC and BASHH guidance.
• Long-term mutually monogamous with a shared negative baseline: no routine retesting required.
• After any condomless encounter with a new partner, a barrier failure, or a partner notification: test after the correct window.
• Pregnancy: HIV, syphilis and hepatitis B are screened routinely in most countries; chlamydia depending on age and local policy.

Window periods

Testing too early produces a false negative. These are the intervals after exposure at which a negative result is reliable.

If you test early and it is negative, retest at the full window. A negative test says nothing about exposures after the sample was taken.

Three-site testing

A urine sample tests the urethra only. It does not test the throat or rectum. Ask explicitly for throat and rectal swabs if you have had receptive oral or anal sex — a large proportion of gonorrhoea and chlamydia in men who have sex with men and in many women is extragenital and would be missed by urine alone. Chandra et al. and multiple screening studies have found that urine-only testing misses the majority of infections in people with extragenital exposure.

Self-collected swabs are as accurate as clinician-collected for most NAAT-based tests and are offered by most services.

Herpes serology: why it is usually not offered

Blood tests for HSV detect antibodies, cannot distinguish oral from genital site of infection, have a meaningful false-positive rate for HSV-2 at low index values, and do not change management for someone without symptoms. CDC, BASHH and the USPSTF all advise against routine HSV serology in asymptomatic people. Swab a lesion when there is one. Serology is reasonable in specific situations — a partner with known genital herpes, or pregnancy planning with a serodiscordant couple — and should be discussed rather than added by default.

Types of testing

• Clinic or sexual health service: full range, examination, immediate treatment, partner notification support. Free in many countries.
• Postal self-sampling kits: widely available and validated for chlamydia, gonorrhoea, HIV, syphilis. Follow the sampling instructions precisely; a poorly taken swab is the main cause of an invalid result.
• Rapid HIV self-tests: results in minutes. Any reactive result needs confirmatory lab testing, and the 90-day window applies to antibody-only devices.
• GP or primary care: variable range; ask exactly which infections and which sites are covered, because "a full sexual health screen" means different things in different services.

Talking about results

• "I was last tested on [date] and it covered [infections and sites]. What about you?"
• "Have you been tested since your last partner?"
• "I have [infection]. Here is what that means, and here is what we can do."

A recent negative test is not a guarantee of current status, because of window periods and any exposure since. It is one input alongside barriers, PrEP, vaccination and viral suppression.

Partner notification

If you test positive, previous partners need to know so they can test and treat. Clinics offer anonymous notification and, in many countries, online partner-notification tools that send a message without identifying you. Untreated partners cause reinfection: this is the main reason chlamydia recurs.

Positive results

Bacterial STIs are cured, usually within a week or two, with an abstinence period during treatment. HIV is managed with a single daily tablet for most people and leads to a normal life expectancy and no onward sexual transmission at an undetectable viral load. Herpes is managed and often becomes less frequent over time. HPV usually clears without intervention. None of this is a moral event.

Sources

• CDC. Sexually Transmitted Infections Treatment Guidelines, 2021 and updates; and screening recommendations for MSM.
• BASHH. UK national guideline on sexual health screening, current edition.
• USPSTF. Serologic screening for genital herpes: recommendation statement, 2023.
• Papp JR et al. "Recommendations for the laboratory-based detection of Chlamydia trachomatis and Neisseria gonorrhoeae." MMWR, and updates.
• Delaney KP et al. "Time until emergence of HIV test reactivity." Clinical Infectious Diseases, 2017.
• Public Health England / UKHSA. Extragenital screening evidence reviews, current edition.

Last reviewed: August 2026.