References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
The incubation period is the time between being infected with an STI and when symptoms first appear. Different infections have different incubation periods — some show up within days, others take weeks or longer. Knowing the typical timeframes helps you think about when to test and whether recent symptoms might be connected to specific exposures.
Here’s a clear guide.
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Incubation Periods by Infection
| STI | Typical Incubation | When Testing Becomes Reliable |
|---|---|---|
| Chlamydia | 1-3 weeks | 1-2 weeks |
| Gonorrhoea | 2-14 days | 1-2 weeks |
| Trichomoniasis | 5-28 days | 1-2 weeks |
| HIV (seroconversion illness) | 2-4 weeks | 4 weeks (4th-gen test) |
| Syphilis (primary chancre) | 10-90 days | 3-12 weeks (blood test) |
| Herpes (first episode) | 2-12 days | Swab active lesion |
| Hepatitis B | 6 weeks to 6 months | 6 weeks to 3 months |
| Hepatitis C | 2 weeks to 6 months | 6 weeks to 3 months |
| Genital warts (HPV) | Weeks to months | Visible diagnosis |
| Pubic lice / scabies | Days to weeks | Visible diagnosis |
| Mycoplasma genitalium | 1-3 weeks | 2-3 weeks |
Incubation vs Window Period
These are often confused but mean different things:
- Incubation period: Time from infection to symptoms appearing
- Window period: Time from infection to when testing becomes reliable
Tests can sometimes detect infection before symptoms appear, and symptoms can appear before tests become positive. Both matter for deciding when to test.
Why This Matters
- Testing too early can miss infection
- Symptoms appearing at a typical incubation time can support or rule out certain STIs
- Knowing the timing helps you work out which encounters might be the source
- It informs decisions about PEP (within 72 hours) and PrEP (ongoing)
Testing Strategy After Exposure
- Within 72 hours: Consider PEP for HIV if high-risk exposure
- 1-2 weeks: Can test for chlamydia, gonorrhoea, trichomoniasis
- 4-6 weeks: HIV 4th-generation test, syphilis
- 3 months: Final HIV test if indicated, hepatitis B and C
If Symptoms Appear Sooner
If you develop symptoms within days of exposure, it doesn’t necessarily rule out one STI or prove another. See a clinician for assessment and testing — they can consider the full picture.
Read more: HIV window period | When to test | Seroconversion symptoms
Frequently Asked Questions
How soon can I get tested after a risky encounter?
Chlamydia and gonorrhoea testing becomes reliable from 1-2 weeks. HIV from 4 weeks. Hepatitis from 6 weeks to 3 months.
Can symptoms appear weeks after exposure?
Yes. Some STIs (HIV, syphilis, hepatitis) can take weeks or months before symptoms or test positivity appear.
If I have no symptoms, am I in the clear?
No. Many STIs are silent. Testing at the right time is the only reliable way to know.
Related reading
- Can You Test for STIs While on Your Period?
- Common STI Symptoms in Women
- Does a Vaginal Yeast Infection Smell?
- HIV Risk from Vaginal Sex: What You Need to Know
- How Different STIs Affect Vaginal Discharge
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
