STI testing — what's included, privacy, and the window-period rules

Who should test and when

Reasons to consider STI testing:

• New sexual partner.
• Multiple partners.
• Concerns about a specific exposure.
• Symptoms (unusual discharge, painful urination, sores, persistent flu-like symptoms in the weeks after a new partner).
• A current partner has tested positive for an STI.
• Routine sexual health check-up (BASHH recommends regular testing for sexually active adults, particularly those with new or multiple partners).
• Pre-pregnancy or pre-conception planning.
• Insurance, visa, or employment requirements.
• Reassurance and informed sexual health decision-making.

Many STIs are asymptomatic — the absence of symptoms doesn't mean absence of infection. Chlamydia in particular is often silent in both men and women.

The infections typically tested

Chlamydia (Chlamydia trachomatis). The most common bacterial STI in the UK. Often asymptomatic; can cause urethritis, pelvic inflammatory disease, fertility issues if untreated. NAAT (nucleic acid amplification test) on urine (men) or vulvovaginal swab (women) is the gold standard. Window period: ~2 weeks after exposure.

Gonorrhoea (Neisseria gonorrhoeae). Increasingly common, with rising antibiotic resistance concerns. Similar testing to chlamydia (NAAT on urine or swab). Throat and rectal swabs important if exposure includes those sites. Window period: ~2 weeks.

HIV. Modern 4th-generation antigen/antibody tests detect both p24 antigen and HIV antibodies, giving reliable results from about 4 weeks post-exposure. A negative test at 4 weeks is reassuring; many guidelines suggest confirming at 12 weeks for the highest confidence. PrEP and PEP are available for prevention in higher-risk scenarios — a separate clinical conversation.

Syphilis (Treponema pallidum). A blood test for treponemal and non-treponemal antibodies. Window period: 12 weeks for reliable detection, though some tests detect from 4–6 weeks. Untreated syphilis progresses through stages and causes serious long-term harm — always treatable when caught.

Hepatitis B. Blood test for surface antigen, surface antibody, and core antibody. Window period: 6–8 weeks. Vaccine-preventable if not previously infected.

Hepatitis C. Blood test for antibodies (and confirmatory RNA test if antibodies positive). Window period: 6–9 weeks for antibodies. Modern direct-acting antiviral treatment cures most cases.

Herpes (HSV-1 and HSV-2). Two testing approaches: serology (blood test for antibodies, useful for asymptomatic exposure or recurrent unexplained genital symptoms) or PCR swab of an active lesion (most accurate for symptomatic episodes). Window period for antibodies: 12–16 weeks. Common, often mild, manageable with antivirals.

Mycoplasma genitalium. Emerging STI, increasingly tested for, can cause urethritis and pelvic inflammatory disease. NAAT testing similar to chlamydia.

Trichomonas. Less common in the UK but important in some demographics. Test by swab.

HPV. Tested mainly through cervical screening rather than separate STI panels. No reliable blood test for HPV.

Window periods — the critical concept

Testing too early after exposure gives a falsely reassuring negative result. Each infection has a window between exposure and reliable testing. Approximate windows:

• Chlamydia, gonorrhoea: 2 weeks.
• HIV (4th gen): 4 weeks for high confidence; some early signal possible from 2–3 weeks.
• Syphilis: 12 weeks for highest confidence; 4–6 weeks for some tests.
• Hepatitis B: 6–8 weeks.
• Hepatitis C: 6–9 weeks.
• Herpes serology: 12–16 weeks.

If you've had a recent specific exposure and want fastest possible answers, the test schedule is typically: early test (2–4 weeks) for chlamydia, gonorrhoea, and HIV; comprehensive re-test at 12 weeks for confirmation across syphilis, late HIV, and hepatitis.

For routine asymptomatic screening (no recent specific exposure), a comprehensive panel at any time gives reliable results.

NHS vs private STI testing

NHS sexual health services (sometimes called GUM clinics):

• Free at point of access.
• Comprehensive testing, treatment, partner notification, and follow-up included.
• Designed with privacy and confidentiality in mind — typically separate records from GP.
• Can offer specialist services (PrEP, complex case management, contact tracing).
• Often the right route, especially for symptomatic cases or post-exposure scenarios.
• Access can vary: some areas have wait times, walk-in availability, or self-referral; some require appointment.

Private pharmacy-based STI testing:

• Quick access — often same-day or next-day appointments.
• Discreet, in a private consultation room or via postal kit.
• UKAS-accredited labs (same as NHS).
• Out-of-pocket cost.
• Most positive results can be treated same-day by the pharmacy prescriber; complex cases referred.
• Useful when NHS access is delayed or inconvenient, when privacy is particularly important, or when you want speed.

Neither is strictly better — they serve different needs. The right answer depends on urgency, complexity, privacy needs, and what's accessible.

Privacy considerations

Private pharmacy STI testing offers a high level of privacy:

• Results don't go on your NHS record unless you choose to share them.
• Private consultation rooms ensure clinical discussions stay private.
• Pharmacy-based postal sample options exist for some tests where you don't want to attend in person.
• For positive results that need ongoing treatment beyond a single course, sharing with GP is usually clinically appropriate — but the decision sits with you.

NHS sexual health services also offer good confidentiality — they don't routinely share with GP either — but they do hold separate clinic records.

Sample collection

Most STI tests use one or more of:

• Blood sample. For HIV, syphilis, hepatitis B, hepatitis C, herpes serology. Standard venous draw.
• Urine sample. For chlamydia, gonorrhoea (especially in men). First-catch urine (the very start of urination), ideally not having urinated for 1–2 hours before.
• Vulvovaginal swab. Self-collected for women — more sensitive than urine for chlamydia and gonorrhoea. Done in private.
• Throat swab. If oral exposure relevant.
• Rectal swab. If anal exposure relevant.
• Lesion swab. For active herpes outbreaks.

The full panel typically involves blood + urine or swab — 5–10 minutes of sample collection.

What to expect after a positive result

For most common STIs:

• Chlamydia, gonorrhoea, trichomonas. Short antibiotic course. Most resolve cleanly; re-test at 3 months recommended for gonorrhoea given resistance concerns.
• Syphilis. Penicillin injection (sometimes multiple doses depending on stage). Treatment is curative.
• HIV. Modern antiretroviral therapy. Single-pill once-daily regimens for most patients. Life expectancy near-normal for those diagnosed and treated. NHS HIV care is excellent and centrally funded.
• Herpes. Antiviral medication for outbreaks; suppressive therapy for frequent recurrences. No cure but very manageable.
• Hepatitis B. Vaccination if not previously infected; specialist hepatology care for chronic infection.
• Hepatitis C. Direct-acting antiviral therapy cures most cases over 8–12 weeks.

Partner notification is part of responsible care. For most STIs, current and recent sexual partners should be notified so they can also test and treat. Pharmacy-based services can support partner notification anonymously where you prefer.

Symptoms to know about

Common STI-suggestive symptoms in men:

• Painful urination.
• Unusual urethral discharge.
• Testicular pain.
• Genital sores, blisters, or warts.
• Rash on hands or feet (possible syphilis).

Common STI-suggestive symptoms in women:

• Unusual vaginal discharge.
• Painful urination.
• Painful sex.
• Bleeding between periods or after sex.
• Pelvic pain.
• Genital sores, blisters, or warts.

Many infections are asymptomatic, so absence of symptoms doesn't mean absence of infection.

Post-exposure considerations

If you've had a high-risk exposure (e.g. unprotected sex with a partner of unknown HIV status):

• PEP (post-exposure prophylaxis): can prevent HIV transmission if started within 72 hours of exposure. Available via NHS sexual health or A&E. The sooner, the better.
• Emergency contraception: available from any pharmacy without prescription if pregnancy is also a concern.
• STI testing at the appropriate windows.

PrEP — pre-exposure HIV prevention

PrEP (daily or event-based oral medication) prevents HIV transmission for people at higher risk. NHS PrEP is available through sexual health clinics; private PrEP is also available. A clinical conversation about whether PrEP is appropriate is a separate discussion from routine STI testing but often comes up.

Vaccination — a key prevention angle

• HPV vaccination protects against most cervical cancer and genital wart-causing HPV strains. Routine UK schedule from age 12; catch-up available privately.
• Hepatitis B vaccination recommended for people at higher exposure risk (multiple partners, men who have sex with men, certain travel destinations, healthcare workers).
• Hepatitis A vaccination sometimes relevant in specific scenarios.
• Mpox vaccination available for some higher-risk groups.

The Leicester clinic context

We process STI testing through UKAS-accredited labs (the same labs the NHS uses), with 24–48 hour turnaround for blood tests and 2–4 days for some swabs. All testing is done in a private consultation room with the same Independent Prescriber who can dispense treatment for most positive results same-day. Discreet packaging for postal options. No GP record entry by default.

How this fits with other testing

STI testing sits separately from most other private bloods. For general health screening, see our private blood test guide. For other tests sometimes done alongside (vitamin D, thyroid, iron), see our specific guides on thyroid testing, vitamin D, iron / ferritin, and menopause hormones.

The next step

If you want STI testing — routine check-up, post-exposure concern, or symptom-driven — book a discreet same-day or next-day appointment. We'll talk through which panel is right, take samples in a private room, and get results to you within 24–48 hours. Treatment for most positive results can be dispensed same-day.