STI Testing Windows Explained | Day 1–90 Timelines

What Are STI Testing Windows?

STI testing windows refer to the minimum time that must pass after potential exposure before a test can reliably detect an infection. Testing during the window period may produce a false-negative result — meaning the infection could be present but not yet detectable.

Key points about STI testing windows:

Each infection has a different window period
Testing too early may give a false-negative result
Some infections are detectable within days; others take weeks or months
Window periods apply to all test types, including blood, urine, and swab tests
Retesting after the full window period may be recommended in some cases

For a broader look at what happens when you test before the window closes, see our article on testing too early for STIs.

Understanding STI Incubation Periods

The incubation period is the time between contracting an infection and when symptoms may first appear. This is distinct from the testing window, although the two are related. Some people experience symptoms before a test can detect the infection, whilst others may never develop symptoms at all.

Common Non-STI Causes of Post-Exposure Symptoms

Many symptoms people associate with STIs have entirely unrelated causes:

Friction or irritation — physical activity, tight clothing, or vigorous sexual contact
Hormonal fluctuations — particularly in women
Shaving or grooming reactions — razor bumps, ingrown hairs, and folliculitis
Allergic reactions — latex, lubricants, soaps, or detergents
Skin conditions — eczema, dermatitis, and other benign conditions
Urinary tract infections — burning, urgency, and discomfort

STI Testing Windows: Day 1 to Day 90 Timeline

Days 1–7: Very Early Period

During the first week after potential exposure, most STI tests are unlikely to produce accurate results. The body has not yet had sufficient time to mount a detectable immune response. Our guide on how soon after unprotected sex to get tested provides further context on early testing decisions.

Days 7–14: Early Detection Window

Some bacterial infections begin to become detectable during this period.

Chlamydia — may be detectable via urine test or swab from approximately 7–14 days after exposure
Gonorrhoea — similar to chlamydia, testing via urine or swab may become reliable from around 7–14 days

A chlamydia test or gonorrhoea test during this window may provide early detection.

Days 14–28: Two to Four Week Window

Chlamydia and gonorrhoea — testing accuracy improves further; most guidelines consider two weeks a reasonable minimum
Trichomoniasis — may be detectable from around two weeks onwards via swab testing
**Early syphilis — some blood tests may begin to detect syphilis antibodies from around three to four weeks
HIV (4th generation tests)** — modern combination antigen/antibody tests may begin to detect HIV from approximately 28 days

Days 28–45: One Month Plus

HIV — 4th generation laboratory tests are considered highly accurate from around 45 days post-exposure
Syphilis — a syphilis test is typically recommended from around 4–6 weeks after exposure
Hepatitis B — may be detectable from approximately 6 weeks onwards
Hepatitis C — antibody testing may require up to 12 weeks for reliable results

Days 45–90: Full Window Period

HIV — testing at 45 days with a 4th generation test is highly reliable; testing at 90 days is considered conclusive
Syphilis — retesting at 12 weeks (approximately 84 days) may be recommended if initial tests were negative
Hepatitis B and C — confirmatory testing may be advised at the 12-week mark

For comprehensive assessment, a full STI screen after the appropriate window period provides the most thorough approach.

When STI Testing May Be Sensible

Symptoms persist beyond a few days — particularly discharge, sores, or pain (if you noticed symptoms within the first few days, this guide may also help)
Unprotected sexual contact with a new or casual partner — see our guide on what tests you really need after unprotected sex
A partner has been diagnosed with an STI
Multiple sexual partners — regular testing may be appropriate
Symptoms worsen or spread
Planning a new relationship — some individuals choose to test before entering a new sexual relationship

How STI Testing Works

Types of Tests

Urine tests — commonly used for chlamydia and gonorrhoea detection
Swab tests — taken from the affected area (genital, oral, or rectal depending on exposure)
Blood tests — used for HIV, syphilis, hepatitis B, and hepatitis C

The Process

A brief confidential consultation to discuss exposure history and any symptoms
Appropriate samples collected based on individual risk factors
Samples sent to an accredited laboratory for analysis
Results provided confidentially, typically within a few working days

Frequently Asked Questions

Can I test for STIs the day after exposure?

In most cases, testing immediately after exposure will not provide reliable results. Most infections require at least 7–14 days before they become detectable.

Does a negative test during the window period mean I'm clear?

Not necessarily. A negative result during the window period may be a false negative. Retesting after the full recommended window is generally advised.

Should I get tested if symptoms disappear on their own?

Symptoms that resolve may still warrant testing, particularly if there was unprotected contact with a new partner.

How soon after exposure can chlamydia be detected?

Chlamydia may be detectable from approximately 7–14 days after exposure, with accuracy improving further at two weeks and beyond.

When to Seek Medical Advice

Certain situations may require prompt medical attention:

Severe pain in the genital or pelvic area
Open sores or ulcers that do not heal
Fever accompanied by genital symptoms
Significant swelling, redness, or spreading rash
Difficulty urinating or blood in urine
Symptoms that progressively worsen over several days

Confidential STI Testing in the UK

If you are concerned about possible STI symptoms or recent exposure, confidential STI testing appointments are available at our UK clinic. Our team can help advise on appropriate testing timelines and which tests may be most relevant to your circumstances. Book a confidential appointment at a time that suits you.

Compliance & Regulatory Information

This content has been produced in accordance with the following UK regulatory and advertising standards:

CQC (Care Quality Commission): Our clinic operates in accordance with CQC fundamental standards of quality and safety.
GMC (General Medical Council): All clinical services operate under appropriate medical governance, and content has been reviewed to ensure alignment with GMC Good Medical Practice standards.
NMC (Nursing & Midwifery Council): Our nurse-led clinic adheres to NMC standards for professional practice, and all content aligns with guidance on providing accurate, evidence-based health information.

Disclaimer: This article is for general informational purposes only and does not constitute medical advice, diagnosis, or treatment. The information provided is not a substitute for professional clinical judgement. Sexual health concerns should be assessed on an individual basis by a qualified healthcare professional. If you are experiencing persistent, severe, or worsening symptoms, please consult an appropriate healthcare service. Our clinic provides private STI testing services only — we do not prescribe medication, provide ongoing treatment, or offer GP services.

Written: 8 March 2026 | Next Review Due: 8 March 2027

STI Testing Windows Explained (Day 1–90 Timelines)