Getting tested at the right time is just as important as getting tested at all. Every STI has a window period — the time between exposure and when the infection becomes detectable. Testing too early can produce a false negative, giving you misleading reassurance.
Recommended Window Periods
The following are the minimum waiting times before testing is likely to be accurate:
- Chlamydia and gonorrhoea – 2 weeks after exposure
- HIV (4th generation test) – 45 days after exposure (conclusive at 90 days)
- Syphilis – 4 weeks, though some tests may require up to 12 weeks for a conclusive result
- Hepatitis B – 6 weeks after exposure
- Hepatitis C – 6 to 12 weeks after exposure
- Herpes – typically diagnosed from symptoms; blood tests may take 12 weeks to be reliable
When to Get Tested
The NHS and BASHH recommend testing in the following situations:
- After unprotected sex with a new partner or someone whose STI status you do not know
- If a partner tells you they have been diagnosed with an STI
- If you have symptoms — discharge, sores, pain during urination, or unusual bleeding
- Before starting a new sexual relationship — a good practice for both partners
- If you are pregnant — routine antenatal screening includes HIV, syphilis, and hepatitis B
Routine Screening Recommendations
Even without symptoms, regular screening is advisable:
- Annual chlamydia screening is recommended for all sexually active people under 25 in England (via the National Chlamydia Screening Programme)
- Men who have sex with men (MSM) are advised to test every 3 months if they have multiple partners, or annually at a minimum
- People with multiple partners should consider testing every 3 to 6 months
Where to Get Tested
You can access STI testing through several routes in the UK:
- Free home testing kits via your local NHS sexual health service
- GUM (genitourinary medicine) clinics — walk-in or by appointment
- Your GP surgery
- GPhC-registered online pharmacies offering private postal kits
If in doubt, get tested. Most STIs are easily treated when caught early, and regular screening is one of the most effective ways to protect your health and your partners.