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.
An undetectable HIV viral load means that antiretroviral treatment has suppressed the virus to levels too low for standard tests to measure — typically below 20-50 copies per millilitre of blood. Being undetectable means you cannot pass HIV on sexually (U=U — Undetectable = Untransmittable) and that your immune system can recover and stay healthy.
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What Viral Load Numbers Mean
| Level | Meaning |
|---|---|
| Undetectable (<20-50) | Treatment working; no sexual transmission |
| Low (50-200) | Blip possible; usually not concerning |
| Detectable (>200) | May indicate adherence issues or resistance |
| High (10,000+) | Untreated or treatment not working |
U=U: The Evidence
- Major studies (PARTNER 1&2, HPTN 052) found zero transmissions from undetectable partners
- Over 100,000 acts of condomless sex studied
- Endorsed by NHS, WHO, BHIVA and 1,000+ organisations
Staying Undetectable
- Take ART every day as prescribed
- Attend clinic appointments for monitoring
- Don’t stop treatment without medical advice
Read more: HIV and the immune system | U=U for partners | Viral load logs
Frequently Asked Questions
Does undetectable mean cured?
No — HIV is suppressed, not eliminated. Treatment must continue.
Can I stop condoms if undetectable?
For HIV, yes — U=U. Condoms still protect against other STIs.
How long does it take to become undetectable?
Usually 3-6 months after starting ART.
Related reading
- Injectable HIV Treatment: Everything You Need to Know
- Are HIV Tests Accurate If You're on PrEP, PEP or ART?
- CD4/CD8 Ratio: What It Means and Why It Matters
- CD4 Counts Explained: What Your Numbers Mean
- Changing HIV Treatment: When, Why and How
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.
