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.
Fostemsavir (brand name Rukobia) is a novel HIV attachment inhibitor approved in 2020. It’s specifically designed for adults with multi-drug resistant HIV-1 infection who cannot construct an effective regimen from existing drugs. Fostemsavir represents a new class of HIV medication with a unique mechanism.
How Does Fostemsavir Work?
Most HIV drugs target enzymes the virus uses to replicate (reverse transcriptase, protease, integrase). Fostemsavir is different: it blocks the very first step of HIV infection by binding to HIV’s gp120 envelope protein. This prevents the virus from attaching to CD4 cells in the first place.
Because fostemsavir targets a completely different part of HIV from other drugs, it’s effective against strains that are resistant to multiple other classes.
Who Is Fostemsavir For?
Fostemsavir is only approved for heavily treatment-experienced adults with multi-drug resistant HIV who:
- Have failed multiple prior antiretroviral regimens
- Cannot construct an effective regimen from other available drugs
- Have HIV that is sensitive to fostemsavir
It’s not used in first-line treatment or for treatment-naive patients.
Dosage
- 600mg (one tablet) twice daily with or without food
- Always combined with an optimised background regimen
Side Effects
- Nausea
- Diarrhoea
- Headache
- Rash
- QT interval prolongation (heart rhythm changes) — monitored with ECG
Read more: What is HIV? | HIV drug resistance
Frequently Asked Questions
Is fostemsavir available on the NHS?
Yes, for patients meeting the strict criteria (multi-drug resistant HIV without other viable options). Access is through specialist HIV centres.
How does fostemsavir differ from other HIV drugs?
It’s an attachment inhibitor — it prevents HIV from attaching to cells in the first place, rather than blocking enzymes inside the virus. This unique mechanism makes it effective against highly resistant HIV strains.
Related reading
- Choosing the Right PrEP Drug: Truvada vs Descovy
- Dovato for HIV: A Two-Drug Regimen
- Triumeq for HIV: A Straightforward Guide
- Efavirenz for HIV: An Older NNRTI Still in Use
- Eviplera: How This Anti-HIV Drug Works
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.
