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.
Blood tests are used to screen for several important STIs including HIV, syphilis, hepatitis B and hepatitis C. They detect antibodies, antigens or viral material in your blood. Not all STIs are detected by blood — chlamydia, gonorrhoea and trichomoniasis need urine or swab samples instead.
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What Blood Tests Detect
| STI | What’s Detected |
|---|---|
| HIV | Antibodies + p24 antigen |
| Syphilis | Treponemal antibodies |
| Hepatitis B | Surface antigen (HBsAg) |
| Hepatitis C | Anti-HCV antibodies |
| Herpes (HSV) | Type-specific antibodies (not routine) |
What Blood Tests Don’t Detect
- Chlamydia — needs urine or swab
- Gonorrhoea — needs urine or swab
- Trichomoniasis — needs swab
- HPV — detected by cervical screening
- Mycoplasma — needs swab or urine
A Full STI Screen Needs Both
Comprehensive testing combines blood tests (HIV, syphilis, hepatitis) with urine or swab tests (chlamydia, gonorrhoea). Most sexual health clinics and home kits offer both.
Read more: Blood test accuracy | Full blood screen | Home tests
Frequently Asked Questions
Can one blood test cover all STIs?
No — some need urine or swabs.
Is finger-prick testing accurate?
Yes when processed by accredited labs.
How soon can I test?
HIV from 4 weeks; syphilis 3-12 weeks; hepatitis 6 weeks to 3 months.
Related reading
- How Accurate Are Rapid HIV Tests?
- Anonymous STI Testing: What It Means
- Are HIV Tests Accurate If You're on PrEP, PEP or ART?
- Are STI Blood Tests Accurate?
- Before You Get Intimate: Why You Should Ask About STI Testing
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.
